This report is part of our special series on Asia’s Military Modernisation.

What’s new? Amid heightened threats in North East Asia and a perception of growing vulnerability, Japan is loosening post-World War II constraints on its defence forces and acquiring new military capabilities. But Tokyo continues to look to the United States for security, even as it worries about Washington’s reliability. 

Why does it matter? Japan has the world’s fourth largest economy and ninth largest military budget. It hosts more U.S. troops than any other nation. Yet it is struggling in a changing geopolitical order, placing its bets on becoming a more capable partner to the U.S. while it weighs the pursuit of strategic autonomy. 

What should be done? Japan and the U.S. should clarify their respective roles and responsibilities in the event of a conflict, while Tokyo enhances its institutional analytic capacity on defence issues, deepens its partnerships with like-minded countries to uphold its vision of a Free and Open Indo-Pacific, and reinvigorates channels of communication with Beijing.

Japan is building up its military to meet greater security challenges and to support its vision of international order based on connectivity, trade and international law. Its 2022 National Security Strategy articulated plans for acquiring a more potent military, including long-range precision missiles, and deepening both the U.S. alliance and security partnerships with like-minded countries. The Strategy noted the threats posed by North Korea and China and highlighted Russia’s all-out invasion of Ukraine as a possible harbinger of war in Asia. The Trump administration’s lack of respect for the post-World War II order is likely to lend further impetus to Japan’s rearmament and defence cooperation with non-U.S. partners. To promote its interests and those of regional peace and security, Japan will need to divide its energies: developing new capabilities (including greater analytic proficiency); investing in its cornerstone alliance with the U.S.; cultivating new security partnerships to enhance deterrence; and pursuing diplomacy with all key regional actors, including potential adversaries like China, to manage escalation risks.

Japan has been slowly loosening constitutional constraints on its military since forming the Japan Self-Defense Forces in 1954. The 2022 National Security Strategy, along with the National Defense Strategy and the Defense Buildup Program, represent a crystallisation of efforts to allow the military to obtain capabilities that will better reflect Japan’s economic heft and position it to contend with heightened threats. China increasingly preoccupies defence planners in Tokyo, who assess that Beijing is intent on projecting military power beyond the first island chain – a Cold War-era construct referring to Japan, Taiwan and the Philippines as a barrier restricting Chinese access to the Pacific. The strategists worry that Beijing may seek to take Taiwan by force, leaving Japan isolated in a region where China is increasingly dominant. China’s vehement response to Prime Minister Sanae Takaichi’s mid-November comments about a potential Japanese role in defending Taiwan only serves to heighten Japan’s sense of vulnerability.

Japan has relied on the U.S. as the ultimate guarantor of its security in the post-war era, with U.S. bases in Japan serving as the foundation of a regional security architecture aimed at deterring, first, the Soviet Union and, later, North Korea and China. But U.S. protection has come at the cost of Japan’s strategic autonomy, while doubts about U.S. commitment have intensified with the rise of President Donald Trump and the “America first” credo. Since 2016, Japan has promoted the vision of a Free and Open Indo-Pacific, based on shared principles such as the rule of law, freedom of navigation and free trade; the pursuit of economic prosperity through enhanced connectivity; and a commitment to peace and security. Japan’s advocacy of these principles is based on its identity as a maritime trading nation that relies on norms, rules, institutions and international law for its prosperity and protection from harm. Washington’s retreat from championing this international order is profoundly unsettling for Tokyo.

Against this backdrop, Japan is pursuing a threefold approach as it seeks to assert itself and protect its interests in the regional security order: advancing its own defence capabilities; maintaining and deepening its alliance with the U.S.; and expanding partnerships in Asia and beyond. Japan has pledged to raise defence spending to 2 per cent of GDP by 2027, decisively abandoning an informal 1 per cent cap, and it is on track to reach that goal. Among other priorities, Japan is acquiring “counterstrike” capability, or missiles capable of hitting targets on the Asian mainland, increasing the jointness of its ground, maritime and air forces, and bolstering defences in its south-western islands.

But these objectives are easier identified than achieved. Though there is broad domestic consensus on the need for a stronger military, Japan faces serious impediments to achieving its aims, including fiscal limitations amid a weak economy, demographic constraints as its population dwindles, a limited defence industrial base and political uncertainty.

For these reasons, most Japanese analysts and officials believe that the U.S. alliance must remain the linchpin of Japan’s national security for the foreseeable future, notwithstanding the concerns raised by the Trump administration’s posture toward allies generally and in some cases Japan specifically. There is no ready alternative to the U.S. as guarantor of Japan’s security. One rationale for Japan’s investment in enhanced military capabilities is to keep the U.S. engaged in the region and committed to Japan’s defence. The hope is that by providing a reliable operating environment for the U.S. and shouldering more of the burden of deterrence, Tokyo will demonstrate its value to Washington. Japan’s security policy and national defence are enmeshed with the presence of U.S. forces in Japan and the extended deterrence provided by U.S. nuclear umbrella since the Cold War.

Prime Minister Takaichi has pledged to revise Japan’s national security strategy, defence strategy and defence buildup plan in 2026, ahead of schedule. Japanese planners will thus soon have an opportunity to refine priorities. The list of steps to consider is long. Tokyo should look to build up its analytic strength when it comes to national security issues so that it can better assess how to match limited resources to strategic ends. Given the maritime and airborne nature of the threats facing Japan, Tokyo should rectify the dominance of its Ground Self-Defense Forces in its force structure. Japan also needs to further enhance the jointness of its Self-Defense Forces, including through more realistic training scenarios. Tokyo and Washington should work with greater urgency to determine a command-and-control structure that can better meet the demands of a conflict in East Asia. At the same time, Japan should continue to deepen defence partnerships with like-minded countries to bolster deterrence.

Finally, deterrence should be balanced by diplomacy. Japan needs to maintain its channels of communication with China to ensure that red lines and intentions are clearly conveyed. In this way, the two countries can work together to keep any danger of confrontation at bay.

Tokyo/Bangkok/Brussels, 12 December 2025

Japan, which has the fourth largest economy on earth and the ninth largest military budget, perceives itself to be increasingly vulnerable as the world enters “a new era of crisis”.
1
“Defense of Japan 2025”, Japanese Ministry of Defense, p. 15; “The Military Balance 2025”, International Institute for Strategic Studies, 2025. Germany supplanted Japan as the world’s third largest economy in 2024. Leika Kihara and Tetsushi Kajimoto, “Japan unexpectedly slips into recession, Germany now world’s third-biggest economy”, Reuters, 14 February 2024.Hide Footnote  Its only ally, the United States, remains the pre-eminent global power, economically and militarily, even as its relative clout declines and its commitment to upholding the post-World War II international order seems to abate. Japan hosts some 55,000 U.S. troops, more than any other country, and is vital to U.S. strategy in the Indo-Pacific. Tokyo and Washington traditionally describe the alliance as the cornerstone of Asian security. Japan champions what it calls a free and open dispensation based on international law, which it sees as threatened by countries willing to use force to change the status quo.
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“Diplomatic Blue Book 2024”, Japanese Ministry of Foreign Affairs.Hide Footnote

In December 2022, Japan issued a National Security Strategy stating that “Japan’s security environment is as severe and complex as it has ever been since the end of World War II”.
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“National Security Strategy of Japan”, Prime Minister’s Office of Japan, 16 December 2022. Hereafter NSS 2022.Hide Footnote  It cited China’s growing military capabilities and North Korea’s nuclear intimidation. It called Russia’s full-scale invasion of Ukraine a blow to the foundations of international order; according to Japanese leaders, “Ukraine today may be East Asia tomorrow”.
4
Fumio Kishida, “Keynote address”, speech to Shangri-La Dialogue, Singapore, 10 June 2022; “Biden and Kishida forge new partnership, eyeing China and Russia”, Reuters, 11 April 2024; “Shigeru Ishiba on Japan’s New Security Era: The Future of Japan’s Foreign Policy”, Hudson Institute, 25 September 2024.Hide Footnote  The National Security Strategy, along with the contemporaneous National Defense Strategy and the Defense Buildup Program, known collectively as “the three documents”, articulated plans to reinforce Japan’s military capabilities, deepen its alliance with the U.S. and expand its defence relationships with like-minded countries.

Recent events have only increased Japan’s sense of threat. North Korea’s nuclear arsenal is growing, and Pyongyang has repeatedly test-launched ballistic missiles since Sanae Takaichi became Japanese prime minister in October. Tokyo is troubled by Russia’s partnerships with North Korea and China, including its regular combined military exercises with the People’s Liberation Army. Tensions with China rose sharply with Takaichi’s comment in the Diet that a naval blockade of Taiwan could be classified as a “survival-threatening situation” under Japanese law, permitting use of the Japan Self-Defense Forces (JSDF).
5
 “What to know about China and Japan’s escalating spat over Taiwan”, BBC, 18 November 2025.Hide Footnote  Beijing responded furiously.
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“China sends coast guard to disputed islands as row with Japan escalates”, Financial Times, 16 November 2025.Hide Footnote  Spats such as this one contribute to a palpable sense that Japan is living in an increasingly dangerous neighbourhood and must prepare for challenging times ahead.

There is a growing sense of unease among Japanese analysts about the extent to which Japan can rely on the U.S. alliance to manage these threats. The U.S. National Security Strategy published in late November is likely to deepen these concerns. The document nods to familiar themes that might be reassuring to Japanese strategists, including commitments to enhancing deterrence and maintaining a free and open Indo-Pacific, even as it presses allies for greater defence spending.
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“National Security Strategy of the United States of America”, White House, November 2025.Hide Footnote  But the strategy’s jaundiced view of the international order, which Tokyo sees as the foundation of its prosperity and security, can only be discomfiting to Japan.

This report, part of Crisis Group’s series on Asia’s military modernisation, examines the evolution of Japan’s security policy.
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The previously published instalments in this series are Crisis Group Asia Reports N°347, Asia in Flux: The U.S., China and the Search for a New Equilibrium, 15 May 2025; and N°349, Riding Unruly Waves: The Philippines’ Military Modernisation Effort, 12 August 2025.Hide Footnote  It proceeds to discuss how these changes can be best harnessed to efforts to preserve regional stability and deter military adventurism. It is based on interviews with Japanese and foreign security experts, former and current Japanese and U.S. officials, and retired and serving military officers of the JSDF and U.S. armed forces, conducted between August 2024 and November 2025. Some 17 per cent of the interviewees were women, reflecting the proportions of men and women in these professions in both countries.

Japan’s security policies and force posture have evolved steadily since the JSDF was established in 1954, shaped by the interplay of post-war anti-militarism, domestic politics and threat perceptions. Article 9 of the post-war constitution states that Japan will “forever renounce war as a sovereign right of the nation and the threat or use of force as means of settling international disputes” and “prescribes the renunciation of war, the prohibition of war potential and the denial of the right of belligerency of the state”.
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“The Constitution of Japan”, Prime Minister’s Office of Japan, 3 November 1946.Hide Footnote  Japan is thus commonly described as pacifist, and Japanese society has indeed tended to view the use of force in world affairs with scepticism.
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Brad Glosserman, “A plea and a promise for 2023: No more ‘pacifism’”, Japan Times, 3 January 2023.Hide Footnote  But Japan’s leaders have interpreted Article 9 to allow for the exercise of the right of self-defence, and calling the country pacifist fails to account for the existence of the JSDF or for Tokyo’s reliance on U.S. military power to defend the country should it be attacked.

Indeed, Tokyo is toughening its posture, as it has come to regard its three nuclear-armed neighbours – North Korea, Russia and China – as growing threats to the regional and international order.

Japan looks at North Korea as dangerous principally because of its ballistic missiles and nuclear weapons.
11
 Crisis Group Asia Report N°100, Japan and North Korea: Bones of Contention, 27 June 2005.Hide Footnote  Pyongyang’s missile tests in the Sea of Japan in the 1990s prodded Tokyo to develop ballistic missile defences, which were first deployed in 2008. Its nuclear weapons, first tested in 2006, elevated it to an existential threat in Japanese eyes. Along with this arsenal, North Korea’s unpredictability spurred debate in Japan about developing “enemy base attack capabilities”, the ability to credibly threaten counter-attacks on missile launch sites in order to deter Pyongyang from striking.
12
 Hideya Kurata, “North Korea’s Nuclear Posture and Japan’s Responses” in Leszek Buszynski, ed., Handbook of Japanese Security (Amsterdam, 2024), pp. 326-328.Hide Footnote  North Korea continues to menace Japan with its ballistic missile tests. In October 2024, it launched an inter-continental ballistic missile that flew for 86 minutes, over 7,000km, the longest distance of any North Korean missile to date.
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 Crisis Group interview, retired Japanese admiral, Tokyo, 1 November 2024. See also “North Korea tests new ICBM as its troops appear set to join Ukraine war”, Washington Post, 31 October 2024.Hide Footnote  Of particular concern to Japanese analysts is the possibility that the U.S. could be deterred from coming to Japan’s defence because North Korea can threaten U.S. cities. Moreover, around that time, Pyongyang also firmed up its cooperation with Moscow, a partnership Tokyo regards with trepidation.
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 Crisis Group interviews, security experts, Tokyo, October-November 2024; March 2025.Hide Footnote

Japan’s perception of the threat posed by Russia has grown considerably over the past decade. The two countries never signed a peace treaty after World War II and remain at loggerheads over four Russian-occupied islands known in Japan as the Northern Territories and in Russia as the Southern Kuriles. In Japan’s view, Russia’s 2022 invasion of Ukraine is “a serious violation of international law prohibiting the use of force [that] shakes the very foundation of the international order”; it has lent further impetus to, and served as justification for, Japan’s policies to develop a more robust military and assume a more active global role.
15
 NSS 2022, p. 6.Hide Footnote  In June 2022, then-Prime Minister Fumio Kishida gave a speech drawing a parallel between Russia’s actions and China’s purported desire to change the security architecture to its advantage in East Asia.
16
 Crisis Group interviews, official at U.S. National Security Council, Washington, 26 September 2024; retired Japanese admiral, Tokyo, 1 November 2024.Hide Footnote  The National Defense Strategy highlights Ukraine’s insufficient capacity to “discourage and deter Russian aggression”, which it depicts as a clear lesson for Japan.
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NSS 2022, p. 8.Hide Footnote

But it is China that Japan sees as the most pressing security challenge, because of its increasingly capable military and assertiveness in the East China Sea. China overtook Japan as the world’s third largest economy in 2010, signalling a shift in the Asian balance of power, and it has since moved into the number two slot behind the U.S. Japan regards it as imperative to deter China from unilaterally changing the status quo by force in Taiwan or the East China and South China Seas.
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Crisis Group interviews, experts, Tokyo, November 2024. See also NSS 2022, pp. 8, 14.Hide Footnote  A 2010 incident, in which a Chinese trawler collided with two Japanese coast guard vessels off the Senkaku/Diaoyu Islands (which sit 140km to the north east of Taiwan), suggested Beijing’s readiness to challenge Japan’s administrative control of these islands.
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 This collision on 7 September 2010 caused a diplomatic standoff. Crisis Group Asia Report N°245, Dangerous Waters: China-Japan Relations on the Rocks, 8 April 2013. Both countries claim the islands, which Japan calls the Senkaku and China the Diaoyu.Hide Footnote  China increasingly sends sea and aircraft into Japan’s contiguous and exclusive economic zones, and infringes upon its territorial waters and airspace.
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In August 2024, a Chinese military aircraft for the first time violated Japanese airspace, over the Danjo Islands off Nagasaki prefecture. The following month, a Chinese aircraft carrier sailed into Japan’s contiguous zone for the first time, in Okinawa prefecture. “Japan says Chinese military violated territorial airspace for first time”, Japan Times, 26 August 2024; “Chinese aircraft carrier Liaoning sails in Japan’s contiguous zone for 1st time”, Yomiuri Shimbun, 18 September 2024. Under the UN Convention on the Law of the Sea, coastal states enjoy sovereignty over a twelve-nautical mile territorial sea where domestic law applies. A contiguous zone extends seaward for an additional twelve nautical miles, in which coastal states may enforce customs, fiscal, immigration or sanitary laws and regulations. The Exclusive Economic Zone affords coastal states sovereign rights to explore, exploit, conserve and manage resources of the maritime space extending 200 nautical miles from the coastline or baseline. The U.S. is not a party to the Convention but applies much of it as customary international law.Hide Footnote  In 2024, some 1,350 Chinese government ships prowled the contiguous zone f0r a total of more than 355 days, setting records for the number of ships and days.
21
Takahashi Kosuke, “China sets record for activity near Senkaku/Diaoyu Islands in 2024”, The Diplomat, 2 January 2025.Hide Footnote

Over the past decade, the locus of perceived Chinese threats has shifted to Taiwan.
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Crisis Group interview, Satoru Mori, professor, Keio University, Tokyo, 9 August 2024.Hide Footnote  In 2006, former Prime Minister Shinzo Abe said “a Taiwan contingency is a Japan contingency”.
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“Taiwan contingency also one for Japan, Japan-U.S. alliance: Ex-Japan PM Abe”, Kyodo News, 1 December 2021. Abe made the comment during an online appearance at a Taipei symposium.Hide Footnote  The reality that Japan could be on the front line of a Taiwan Strait conflict is increasingly difficult for Japanese policymakers to ignore, given the presence of U.S. military bases in Japan and its proximity to Taiwan; Japan’s westernmost island, Yonaguni, is 110km from Taiwan.
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Christopher W. Hughes, “Japan’s ‘Three National Security Documents’ and Defense Capabilities: Reinforcing a Radical Military Trajectory”, Journal of Japanese Studies, vol. 50, no. 1 (2024), p. 178.Hide Footnote Tokyo is also disquieted by Chinese actions in the South China Sea, where Beijing has constructed and militarised seven artificial islands, as Japan imports most of its oil and gas across these waters.
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 Crisis Group interview, security expert, Tokyo, 5 November 2024.Hide Footnote  In June, two Chinese aircraft carriers sailed into the Pacific Ocean simultaneously for the first time, raising concerns about the vulnerability of the eastern Japanese coast.
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“In rare move, Japan releases map showing Chinese aircraft carrier activities”, Japan Times, 18 June 2025.Hide Footnote  Most fundamentally, Japan worries about its prospects for security in a regional order dominated by China.
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Crisis Group interviews, national security experts, Tokyo, August and November 2024; March-April 2025. See also Kei Koga, “Japan’s ‘Indo-Pacific’ Question: Countering China or Shaping a New Regional Order?”, International Affairs, vol. 96, no. 1 (2020), p. 49.Hide Footnote

In the immediate post-war era, Japan’s grand strategy was defined by the Yoshida Doctrine, named after Prime Minister Shigeru Yoshida (1946-1947, 1948-1954), which emphasised economic growth, a highly constrained defence posture and reliance on the U.S. for security.
28
 Richard J. Samuels, Securing Japan: Tokyo’s Grand Strategy and the Future of East Asia (Ithaca, NY, 2007), pp. 29-37, 43-45.Hide Footnote  The Yoshida Doctrine continued to characterise Japan’s approach well after the Cold War, exemplified by the persistence of an “exclusively defence-oriented defence” policy, which aimed to reassure other countries that Japan eschewed aggression and would remain a peaceful country.
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The phrase originated in Diet debate in 1955 but was first used officially in the 1970 Defense White Paper. Toshiya Takahashi, “The Development of Japan’s Security” in Buszynski, Handbook of Japanese Security, op. cit., p. 13.Hide Footnote  Meanwhile, reference to Article 9 allowed Japanese leaders to deflect U.S. demands for greater defence spending.
30
 Richard J. Samuels, “Japan’s Goldilocks Strategy”, The Washington Quarterly, vol. 29, no. 4, (Autumn 2006), p. 112.Hide Footnote  Washington has wanted Tokyo to spend more on defence since the Korean War, even as it has portrayed the U.S. military presence in Japan as the “cork in the bottle” of Japanese militarism.
31
The “cork in the bottle” metaphor is associated with comments by U.S. Marine Corps Lieutenant General Henry Stackpole in 1990, but the concept of the U.S. presence as a brake on Japanese militarism dates to the U.S. rapprochement with China in the 1970s. “Marine general: U.S. troops must stay in Japan”, Washington Post, 26 March 1990; Ishihara Yusuke, “Revisiting the ‘Cap-in-the-Bottle’ Thesis: Negotiations and Disagreements among Japan, China and the U.S. in the Early 1970s”, Strategy & Security, vol. 4 (January 2024).Hide Footnote

Changes in the international environment, especially China’s growing power and irredentism, put the Yoshida Doctrine under increasing strain in the first two decades of the 21^st century. The 2010 National Defense Program Guidelines (NDPG), promulgated during the tenure of the centre-left Democratic Party of Japan (2009-2012), initiated a shift in focus from Russia, the presumed origin of Cold War-era threats, to Japan’s south-western islands near the East China Sea and Taiwan.
32
 Ryo Hinata-Yamaguchi, “Developments and Transformations in Japan’s Defense Planning and Readiness”, in Buszynski, Handbook of Japanese Security, op. cit., p. 119; Christopher W. Hughes, Japan as a Global Military Power: New Capabilities, Alliance Integration, Bilateralism-Plus (Cambridge, 2022), p. 23.Hide Footnote  The 2013 NDPG retained concepts from the 2010 version, including the shift to the south west, but accentuated jointness among the JSDF’s three branches under the rubric of a Dynamic Joint Defense Force.
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“National Defense Priority Guidelines for FY 2014 and Beyond”, 17 December 2013, p. 7. It emphasised development of intelligence, surveillance and reconnaissance, rapid deployment capabilities, relaxation of arms export restrictions and the use of Official Development Assistance for defence purposes. Andrew L. Oros, Japan’s Security Renaissance: New Policies and Politics for the Twenty-first Century (New York, 2017), p. 100; Ken Jimbo, “Foreign and Security Policy: The Pursuit of Strategy”, in Yoichi Funabashi and Koji Nakakita, eds., Critical Review of the Abe Administration Politics of Conservatism and Realism (London, 2023), p. 92.Hide Footnote

During his second term (2012-2020), Prime Minister Abe reformed the policymaking apparatus, establishing the National Security Council in December 2013 as a standing body to coordinate strategy among government agencies, with input from military officers, and to streamline decision-making by giving the premier a greater degree of control.
34
Oros, Japan’s Security Renaissance, op. cit., pp. 133-134.Hide Footnote  Abe followed up in the same year with the first National Security Strategy, introducing the concept of Japan’s “proactive contribution to peace based on the principle of international cooperation”, which framed enhanced military capabilities as a preventive measure that was meant to discourage war and thus was consistent with the country’s anti-militarist norms.
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“National Security Strategy”, Government of Japan, 16 December 2013.Hide Footnote

One of the most consequential developments in the evolution of Japan’s defence posture is the Legislation for Peace and Security passed by the Diet in September 2015. This package of amendments to ten laws formalised reinterpretation of Article 9 to allow Japan to exercise the right of collective self-defence under certain conditions. In practical terms, the JSDF may now support its ally and partners even if Japan’s territory is not attacked but one of its partners is and Japanese leaders deem the nation’s survival to be under threat.
36
 Nobuhisa Ishizuka, “Existential Threats and Deterrence: Japan’s Legal Pathway to Enhanced Collective Security in Asia”, American University International Law Review, vol. 40, no. 2 (2025), p. 263.Hide Footnote  Proponents argued that permitting the JSDF to participate in collective self-defence enhanced Japan’s security by strengthening the U.S. alliance, thereby boosting deterrence, and allowing Tokyo to play a more active role in shaping the regional security order.
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“Press Conference by Prime Minister Abe”, Prime Minister’s Office of Japan, 15 May 2014.Hide Footnote  This reinterpretation of the constitution was the most significant loosening of constraints on the JSDF’s activity since its founding in 1954. It was also enormously controversial, sparking the largest protests in Japan since the 1960s.
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Crisis Group interviews, national security experts, Tokyo, August and October 2024.Hide Footnote

In 2016, Abe introduced the concept of a Free and Open Indo-Pacific (FOIP), offering a framework for Japan’s more assertive foreign policy and defence engagement based on upholding international rules and norms.
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 Takahashi, “The Development of Japan’s Security”, op. cit., p. 24.Hide Footnote  A geostrategic concept meant to mobilise like-minded regional powers, FOIP rests on three pillars: the promotion of shared principles such as the rule of law, freedom of navigation and free trade; the pursuit of economic prosperity through enhancing connectivity; and commitment to peace and security.
40
 Nanae Baldauff and Stephen Nagy, “Reboot, Continuity or Adaptation? Making Sense of Japan’s FOIP Vision Update in the Context of China and Taiwan”, Chinese Political Science Review no. 78 (2024), pp. 81-82.Hide Footnote  The FOIP resonated with Tokyo’s friends. Australia, the U.S., the European Union, India and others issued documents or strategies inspired by FOIP, which remains a symbol of Japan’s greater ambition and capability to shape the regional order.

Two years later, the 2018 NDPG introduced the Multi-Domain Defense Force capable of engaging in “cross-domain operations” in land, sea, air, space and cyberspace, as well as in electronic warfare.
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“National Defense Program Guidelines for FY 2018 and Beyond”, Japanese Ministry of Defense, 18 December 2018, p. 10.Hide Footnote  The 2018 guidelines for the first time listed China before North Korea in Tokyo’s itemisation of security concerns, noting, “China engages in unilateral, coercive attempts to alter the status quo based on its own assertions that are incompatible with the existing international order”.
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Ibid., p. 5.Hide Footnote

A trio of documents lies at the core of Japan’s emergent military strategy. The National Security Strategy, the National Defense Strategy and the Defense Buildup Program released in December 2022, known collectively as the “three security documents”, lay out policy changes aimed at acquiring for Japan a more agile, capable military that will allow it to play a larger role in maintaining peace and security in the Indo-Pacific. The primary objective is “the fundamental reinforcement of … defence capabilities” so that, by 2027, Japan can “take the primary responsibility for dealing with invasions … and disrupt and defeat such threats while gaining the support of its ally and others” and, by 2032, “disrupt and defeat invasions … much earlier and at a further distance”.
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NSS 2022, p. 20.Hide Footnote  While the implicit goal of relying less on the U.S. security umbrella is clearly aspirational on such a tight timeframe, its articulation remains an important expression of Japan’s evolving defence policy.

Beyond what is says about the role Japan seeks to play in its own defence, the Strategy is also notable for what it says about deterrence or, more specifically, what analysts call “deterrence by denial”.
44
Ken Jimbo, “Deterrence by Denial: Japan’s New Strategic Outlook”, Stimson Center, 22 February 2023. Deterrence by denial is often contrasted with deterrence by punishment. “In military affairs deterrence by denial is accomplished by having military forces which can block the enemy’s military forces from making territorial gains. Deterrence by punishment grants him the gain but deters by posing the prospect of war costs greater than the value of the gain”. Glenn H. Snyder, “Deterrence and Power”, Conflict Resolution, vol. 4, no. 2 (1960), p. 163.Hide Footnote  The National Defense Strategy expresses this idea by saying Japan aims to develop military capabilities sufficient to make “the opponent realise that the goal of invasion of Japan is not achievable by military means, and that the damage the opponent will incur makes the invasion not worth the cost”.
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“National Defense Strategy”, Japanese Ministry of Defense, 16 December 2022, p. 11.Hide Footnote  In postulating such an invasion, official documents leave little doubt that China is the adversary Japan’s defence planners envision.
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“Defending Japan 2025” (digest), Japanese Ministry of Defense, p. 16.Hide Footnote  China’s growing military capabilities and provocative activities below the threshold of armed conflict (often referred to as grey-zone tactics) around the Senkaku/Diaoyu Islands have focused minds in Japan. Tokyo is also thinking more about how to help deter China from invading Taiwan, as such an assault would have a profound impact on Japan’s security and raise the possibility of a wider war.

While Tokyo works toward the goal of assuming primary defensive responsibility in the coming years, its defence planning is rooted in current reality. It both relies heavily on U.S. military power and recognises its limitations. One of those is that, since the 2010s, the U.S. military no longer reigns supreme in the seas and skies around Japan, due to China’s advantage in precision missiles.
47
 Ken Jimbo, “Japan’s Security Policy” in Michito Tsuruoka, ed., Japan in an Era of Geopolitics: A New Foreign and Security Policy Direction (Tokyo, 2024), p. 20.Hide Footnote  As a result, it may not be possible to stop hostile forces from achieving landfall. Given that attempting to repel an invasion at the water’s edge “may place friendly forces at risk of annihilation”, Tokyo’s strategy is premised on developing resilience or preserving strength in a conflict’s early stages until allied reinforcements can join the fight in sufficient numbers to prevail.
48
Eric Heginbotham and Richard J. Samuels, “Active Denial: Redesigning Japan’s Response to China’s Military Challenge”, International Security, vol. 42, no. 4 (Spring 2018), p. 138. See also Iwama Yoko and Murano Masashi, “Thinking about Deterrence for Japan and Stability in Asia”, Hudson Institute, 15 October 2021.Hide Footnote

The first pillar of Japan’s three-pronged approach to defence is to bolster its own capacity to deter and fight. In the three security documents, this aim is described as “fundamentally reinforcing defense capabilities”. These efforts build on earlier plans to strengthen the JSDF but are most notable for introducing long-range precision missiles to Japan’s arsenal and addressing deficiencies in cyber-defence.

The three security documents are widely regarded as a watershed in Japan’s defence policy, largely due to the headlines they generated about scrapping the 1 per cent of GDP defence spending cap and acquiring long-range strike missiles. But while the papers herald real changes from the past, they do not signal a full departure. For example, the 2022 Defense Buildup Program exhibits continuity with earlier proposals for major acquisitions and force posture.
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Namely, the 2013 and 2018 National Defense Program Guidelines and Medium-Term Defense Programs.Hide Footnote  The individual branches of the JSDF – Ground, Maritime and Air – did not receive systematic treatment in the three documents and the planned structure of units over the next ten years is “almost identical” to the extant one.
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Heginbotham and Samuels, “Active Denial”, op. cit., pp. 54, 61.Hide Footnote  Even plans for standoff missiles build on acquisitions that had been laid out before.
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“Procurement of a New Missile Defense System, etc. and Strengthening Stand-off Defense Capability”, Japanese Ministry of Defense, December 2020.Hide Footnote

The Defense Buildup Program is also far from a radical break with the past. It specifies a Maritime Self-Defense Forces fleet of 54 destroyers, 22 submarines and twelve patrol vessels, the same numbers as the 2018 plan. That said, the fleet is steadily being modernised, with the retirement of older destroyers and introduction of new Mogami-class frigates capable of carrying out a variety of missions, including surveillance, anti-air, anti-surface and anti-submarine warfare, and minesweeping.
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“New warship to help Japan tackle manpower issues amid growing security threats”, Japan Times, 7 March 2023.Hide Footnote The new naval procurement provides for the acquisition of two Aegis system-equipped vessels for ballistic missile defence, with the first expected in 2028 and the second the following year. These ships replace the Aegis Ashore system that was cancelled in 2020.
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 “Japan’s ASEV Super Destroyer: Fresh details unveiled”, Naval News, 6 March 2025.Hide Footnote

One area where there has been pronounced movement is the air force, which will be growing. It expects to have 430 combat aircraft, including 320 fighters by 2032, an increase over 2018 plans of 90 aircraft.
54
National Defense Program Guidelines 2018, p. 33; and Defense Buildup Program 2022, p. 55.Hide Footnote  Japan is acquiring 147 U.S. F-35 fighters, including 42 F-35Bs capable of short take-off and vertical landing, and it will eventually have the largest F-35 fleet outside the U.S.
55
“Defense of Japan 2024”, Japanese Ministry of Defense, p. 249, note 7; Hughes, Japan as a Global Military Power, op. cit., p. 31.Hide Footnote  Japan received its first three F-35B fighters in August; these jets will eventually operate from two helicopter carriers converted into light aircraft carriers.
56
“Japan receives 3 F-35B Lighting II fighters, 1 faces delays”, USNI News, 7 August 2025.Hide Footnote

That these acquisitions of major military hardware reflect a high degree of continuity with earlier plans indicates that changing threat perceptions and strategic considerations alone do not determine procurement. Bureaucratic politics and the longstanding aspiration of Japan’s conservative politicians for a more “normal” military also shape decision-making.
57
Eric Heginbotham, Samuel Leiter and Richard J. Samuels, “Pushing on an Open Door: Japan’s Evolutionary Security Posture”, The Washington Quarterly, vol. 46, no. 2 (2023), pp. 48, 58-61.Hide Footnote  

Among the novel elements of Japan’s new defence ambitions, none has stirred more controversy than counterstrike, the ability to make precision missile strikes on an adversary’s territory. While Japan has reserved the right to mount retaliatory missile strikes since 1956 (as a feature of its right of self-defence), debate about developing the requisite capability picked up pace in the 2010s and 2020s.
58
Ayumi Teraoka and Ryo Sahashi, “Japan’s Revolutionary Military Change: Explaining Why It Happened under Kishida”, Pacific Affairs, vol. 97, no. 3 (2024), pp. 534-535.Hide Footnote  The perceived need for counterstrike is rooted in the recognition that ballistic missile defence alone is insufficient to deter missile attacks, especially given advances in offensive technology. Moreover, Japan’s existing missile defence, developed to protect the islands from North Korean attack, would be inadequate to deal with a threat from China.
59
Crisis Group interviews, Satoru Mori, professor, Keio University, Tokyo, 9 August 2024; and Shinichi Kitaoka, professor emeritus, Tokyo University, Tokyo, 5 November 2024. See also Shinichi Kitaoka, “Japan’s Defense Agenda – Translating the Abe Reforms into Action”, Nippon, 12 October 2022; and NSS 2022, p. 19.Hide Footnote

Counterstrike is controversial because missiles that can hit mainland Asia call into question the defensive nature of Japan’s military capabilities. Any Japanese counterstrike must align with the Three Conditions for Use of Force, first set out in 1954. There must be a threat to national survival; no other available means of warding off the danger; and the exercise of constraint such that the use of force is limited to the minimum necessary.
60
 Kurata, “North Korea’s Nuclear Posture and Japan’s Responses”, op. cit., p. 327.Hide Footnote These conditions allow for the use of force in self-defence only in extremis.
61
NSS 2022, p. 19.Hide Footnote

In theory, Japan could launch missiles in the event of an attack on the homeland, hitting the adversary’s military sites. But Japan’s current constitutional interpretation would not permit the same missiles to be launched in a pre-emptive attack. The 2022 NSS states, “Needless to say, pre-emptive strikes, namely striking first at a stage when no armed attack has occurred, remain impermissible”.
62
 Ibid.Hide Footnote

This formulation leaves open the question of what Japan would do under the threat of imminent attack, which is widely viewed among international lawyers as covered by the right of self-defence. Debate on this topic within the Japanese government is framed as a discussion about what constitutes initiation of an armed attack rather than one about what renders a threat imminent.
63
Masahiro Kurosaki, “The Dynamics of Japan’s ‘Armed Attack Initiation’ Doctrine and Anticipatory Self-Defense”, Lawfare, 1 September 2020.Hide Footnote  Whether the line would be crossed when an adversary’s rocket is fuelled, or a launcher goes vertical, is not clear. Tokyo’s position is that any decision about whether and when to launch Japanese missiles will take into consideration global politics at that moment.
64
 Ibid.Hide Footnote

The counterstrike capability also exists within significant operational limits. It is not, in practice, an autonomous capability – meaning that Japan does not possess a complete “kill chain”, with the capacity to find and track targets, launch attacks, and assess damage. It must rely on the U.S. for such data.
65
Crisis Group interview, Satoru Mori, professor, Keio University, Tokyo, 9 August 2024. See also Hughes, Japan as a Global Military Power, op. cit., p. 38; and Joseph Ross, “What’s missing from Japan’s defense buildup?”, The Diplomat, 4 April 2024.Hide Footnote

Against this backdrop, Japan is still developing a doctrine for counterstrike, which requires a shift in mentality from territorial defence to a broader geographic remit as well as a theory of escalation management.
66
Crisis Group interview, Ken Jimbo, managing director, International House of Japan, Tokyo, 26 March 2025. See also Rintaro Inoue, “Will Japan Have the Political Resolve to Use Counterstrike?”, The Washington Quarterly, vol. 47, no. 4 (2024).Hide Footnote  For the first time in 80 years, Japan must consider how adversaries might react to a Japanese counter-attack. At the same time, Japanese officials are anxious to frame new capabilities as consistent with Tokyo’s longstanding “exclusively defence-oriented defence” policy.
67
Hughes, “Japan’s ‘Three National Security Documents’ and Defense Capabilities: Reinforcing a Radical Military Trajectory”, op. cit., p. 157.Hide Footnote

As it works through these issues, Japan is investing in a range of missiles to develop its capacity for counterstrike. As an immediate step, Japan purchased 400 U.S. Tomahawk missiles for accelerated delivery.
68
Crisis Group interview, Satoru Mori, professor, Keio University, Tokyo, 9 August 2024. Japan is the third country, after the U.S. and the UK, to acquire Tomahawk missiles. The deal is for “200 Block IV Tomahawks, 200 Block V Tomahawks and 14 Tactical Tomahawk Weapon Control Systems, along with support, training, maintenance, spares and other ancillary services and items”. “Japan signs deal for 400 Tomahawk land attack missiles”, USNI News, 18 January 2024.Hide Footnote Their 1,600km range will bring Chinese and North Korean military bases within striking distance of Japan.
69
Luke Caggiano, “Japan to purchase U.S. Tomahawk missiles”, Arms Control Today, March 2023.Hide Footnote Japan is upgrading its indigenous Type-12 (surface-, ship- and air-launched) missiles to extend their reach from the current 200km to 900km and, eventually, 1,500km.
70
 Hughes, “Japan’s ‘Three National Security Documents’ and Defense Capabilities: Reinforcing a Radical Military Trajectory”, op. cit., p. 170.Hide Footnote Japan is also developing hyper velocity gliding projectiles and hypersonic missiles, which are difficult to detect and intercept, and procuring air-launched long-range missiles that can be used for counterstrike missions.
71
The 2018 Medium-Term Defense Program calls for acquisition of Joint Strike Missiles for F-35 fighters and Joint Air-to-Surface Standoff Missile-Extended Range for F-15J fighters, with ranges of 500km and 1,000km, respectively. “Progress and Budget in Fundamental Reinforcement of Defense Capabilities: Overview of FY2025 Budget Request”, Japanese Ministry of Defense, 26 November 2024. See also Hughes, Japan as a Global Military Power, op. cit., p. 32.Hide Footnote

The shift of forces to the south west, including Japan’s third-largest island, Kyushu, but particularly the smaller Nansei Islands stretching toward Taiwan, has accelerated in recent years in view of the region’s importance in a Taiwan contingency and China’s increased military activity in the area.
72
 Crisis Group interview, security expert, Tokyo, 5 November 2024. The Nansei (or Ryukyu) Island chain extends 1,200km from Kyushu to Yonaguni, the westernmost island in Japan. It is comprised, from north to south, of the Satsunan, Okinawa and Sakishima island chains.Hide Footnote  In 2022, then-Defense Minister Nobuo Kishi said Japan was attempting to fill a “vacuum in terms of vigilance, surveillance and information-gathering activities” in the Nansei Islands, a strategically important section of the so-called first island chain, which stretches north to south from the Kuril Islands through Japan, Taiwan, the Philippines, Borneo and the Natuna Islands.
73
“Ukraine war shines spotlight on Nansei chain SDF deployments”, Yomiuri Shimbun, 31 May 2022.Hide Footnote  Unofficially, the JSDF calls the shift the “south-western wall strategy”.
74
“Taiwan Crisis and Japan’s Strategy”, Sasakawa USA, 2021, p. 3.Hide Footnote

The JSDF has been establishing garrisons on the Nansei Islands, including coastal observation units and surface-to-ship and air defence missile batteries. Deployment of upgraded Type-12 missiles will plug other gaps in coverage of the Nansei Island straits. Tokyo is also setting up a supply hub on Okinawa – the largest of the Nansei chain – and moving the command of the garrison at its capital Naha to a better protected underground location.
75
Ryo Nemoto, “Japan to allow ground forces across nation to deploy near Okinawa”, Nikkei Asia, 7 January 2023.Hide Footnote  In 2018, the JSDF established the Amphibious Rapid Deployment Brigade, a “proto-marine corps”, based in Sasebo, Kyushu, with the mission of retaking remote islands.
76
 Hughes, Japan as a Global Military Power, op. cit., pp. 24-25.Hide Footnote  

Defence of the Nansei Islands hinges on greater mobility of forces, but transport for these forces is seen in Japanese defence circles as a weak link. The 2022 Defense Buildup Program calls for upgrading the 15th Brigade in Okinawa to a division, while all other divisions “will be operated on the basis of rapid deployment”, ostensibly available to deploy to the south west from bases elsewhere in Japan.
77
 “Defense Buildup Program”, Government of Japan, 16 December 2022, p. 19; “Defense of Japan 2024”, op. cit., p. 230. A Ground Self-Defense Force brigade is made up of 3,000-4,000 troops and a division of 6,000-9,000.Hide Footnote  To help with logistics, in March, the JSDF activated the Maritime Transport Group, with a focus on moving troops, equipment and supplies among the Nansei Islands.
78
“SDF maritime transport group boosts mobility in contingencies”, Jiji, 22 July 2025.Hide Footnote  It is a joint unit, with some 90 per cent of its personnel drawn from the country’s ground forces, but also operating two ships, with plans for a fleet of ten by 2027.
79
“SDF launches first maritime transport unit for fast response”, Asahi Shimbun, 7 April 2025.Hide Footnote  The Defense Buildup Program also provides for acquisition of six transport aircraft and thirteen aerial refuelling/transport aircraft.
80
“Defense Buildup Program 2022”, op. cit., p. 53.Hide Footnote  The government is working to improve civilian facilities – including eleven airports and 25 ports throughout Japan – for military use in emergencies and contracting private vessels for maritime transport.
81
 In April, Tokyo added eight sites in seven prefectures as “designated-use airports and ports” for emergency use by the JSDF. “Government to add airports and ports to ‘special use’ list in preparation for emergencies”, Sankei Shimbun, 1 April 2025.Hide Footnote

Japan is also improving civil defence in the Nansei Islands, including plans for evacuating civilians from remote locales. The government has previously neglected these matters, and it could lose local support if it does not give them due attention.
82
Crisis Group interviews, defence experts, Tokyo, August 2024; retired Japanese admiral, Tokyo, November 2024.Hide Footnote

Another priority of Japan’s defence buildup is sustainability and resilience – terms that encompass stockpiling ammunition, maintenance of weapons systems and facilities, and the “hardening” of command centres and bases against attack. Neglect of these functions represents a serious impediment to Japan’s ability to engage in anything but a quick war, a prerequisite of the denial strategy. According to a 2020 media report, Japan’s Air Self-Defense Forces could be destroyed in fifteen minutes by enemy missiles, in part because the country has only 80 hardened aircraft shelters on all the U.S. and Japanese bases on its territory.
83
Heginbotham and Samuels, “Active Denial”, op. cit., p. 56.Hide Footnote  The five-year defence buildup plan (2023-2027) allocates fifteen trillion yen ($104 billion) to resilience, a six-fold increase over the previous one.
84
 Hughes, “Japan’s ‘Three National Security Documents’ and Defense Capabilities: Reinforcing a Radical Military Trajectory”, op. cit., p. 166.Hide Footnote  This amount is the single largest slice of the budget allotted for the seven priority areas, and more than half of it (nine trillion yen) is earmarked for ensuring that existing equipment is functional.
85
 By way of comparison, approximately six trillion yen is budgeted for major equipment acquisitions and five trillion for standoff defence. “Defense of Japan 2024”, op. cit., p. 232.Hide Footnote

The 2022 National Defense Strategy recognises that technological advances mean that wars will be fought not only on land, at sea and in the air, but also in outer space, cyber space and the electromagnetic spectrum. Military experts refer to these as realms as “domains”. The National Defense Strategy emphasises the importance of “cross-domain capabilities” to overcome inferiority in any individual area.
86
“National Defense Strategy 2022”, p. 25.Hide Footnote  This expansive aim hinges on development of cyber defences, a longstanding lacuna for Japan, particularly “active cyber defence for eliminating in advance the possibility of serious cyberattacks”.
87
 NSS 2022, p. 23.Hide Footnote  Japan has been slow to acquire such capabilities, particularly because of stringent privacy protections codified in the constitution.
88
Crisis Group interviews, analysts and officials, Tokyo, October-November 2024.Hide Footnote  Japan took a major step forward in May with passage of the Active Cyber Defense Law (effective in 2027) to permit police and the JSDF to neutralise threats emanating from foreign servers.
89
Tae Yeon Eom, “Japan’s New Cybersecurity Law Signals More Offensive Posture”, Asia Pacific Foundation of Canada, 6 June 2025. The JSDF established a Cyber Defense Command in March 2022.Hide Footnote  But the late start means that it is a long way from attaining proficiency in this arena.
90
Crisis Group interviews, analysts, Tokyo, October-November 2024; March 2025.Hide Footnote

As for other technological investments, Japan plans the development of a satellite constellation to track hypersonic missiles and to gather information on targets that could be used for counterstrike.
91
“Japan seeks another record-breaking defense budget for fiscal 2025”, Japan Times, 30 August 2024.Hide Footnote  Tokyo is also developing its own missile warning satellites.
92
 Kota Umeda and Robert S. Wilson, “Space-Based Missile Warning: An Opportunity to Deepen U.S.-Japan Security Cooperation”, Asia Policy, vol. 19, no. 1 (January 2024).Hide Footnote  Japan’s latest defence budget request seeks 128.7 billion yen ($877 million) to acquire large numbers of inexpensive unmanned aerial, surface and underwater vehicles for surveillance and attack to be integrated into a multi-layered coastal defence system.
93
“Japan looks to build drone ‘shield’ in record defense budget request”, Japan Times, 29 August 2025.Hide Footnote

Consonant with the aim of enhancing coordination across domains, Japan has moved to address the lack of jointness among its three military services, which experts have long recognised as a problem.
94
For example, each of the three services has its own geographical command boundaries – four regions for the Air Self-Defense Force and five each for the Ground and Maritime Self-Defense Forces – and none correspond to the others. Heginbotham and Samuels, “Active Denial”, op. cit., p. 59.Hide Footnote  In March, the JSDF Joint Operations Command (JJOC) was established in Tokyo to “build a system that enables seamless cross-domain operations”.
95
“Defense of Japan 2025”, op. cit., p. 20.Hide Footnote  Responsibility for joint operations had belonged to the chief of the joint staff, who is already burdened with responsibility for advising the prime minister and defence minister as well as executing defence orders.
96
The weakness of this arrangement was exposed during the 2011 earthquake and tsunami, when confusion about lines of command hampered disaster response. Crisis Group interviews, security experts, Tokyo, October 2024 and March 2025.Hide Footnote  Now, command-and-control duties will fall upon the JJOC head, a four-star officer with the authority to integrate operations across the three services. Starting with 240 staff, the JJOC is expected to have 280 employees by the end of the next fiscal year.
97
“Why Japan’s new Joint Operations Command is a strategic milestone”, Sankei Shimbun, 25 March 2025.Hide Footnote

A pillar of Japan’s defence buildup is revitalisation of its arms industry. Restrictions on arms exports imposed in the 1960s and 1970s amounted to a prohibition on foreign sales. The weapons industry, driven solely by domestic demand and hampered by small profit margins and social stigmatisation, has shrunk over the years, with more than 100 firms exiting the market since 2002.
98
Miki Matsuo, “Unaddressed Challenges for Defense Policy Reform in Japan”, Center for Strategic and International Studies, 9 May 2024.Hide Footnote  Incremental easing of export restrictions in 2011, 2014 and 2023 and new regulations to lift profit margins have offered the prospect of regeneration, but progress is slow.
99
 Crisis Group interview, security expert, Tokyo, October 2024.Hide Footnote  According to an analyst, “For a long time, we didn’t have enough money. Now, [we] don’t have enough manufacturing power”.
100
Crisis Group interview, Japanese Ministry of Defense official, Tokyo, August 2024.Hide Footnote  In August 2025, Mitsubishi Heavy Industries won a bid to supply Australia with eleven Mogami-class frigates between 2029 and 2034, promising Japan’s largest defence contract and a major boost to its industry.
101
“Winning warship bid gives Japan confidence boost as Tokyo eyes more exports”, Japan Times, 17 August 2025.Hide Footnote

The 2022 National Defense Strategy states: “In today’s circumstance, no country can now protect its own security alone”.
102
“National Defense Strategy 2022”, p. 3.Hide Footnote  In the post-war period, Japan has relied on the U.S. as the guarantor of its security, but in the past decade it has also forged defence partnerships with like-minded countries in the Indo-Pacific and beyond.

A treaty alliance with the U.S. is the bedrock of Japan’s security policy, but it has exhibited the strains typical of such ties. On the U.S. side there are fears of entanglement in foreign conflicts, while on the Japanese side there are doubts about Washington’s commitment. Disagreements over burden sharing are also a persistent feature of the relationship.

Unlike the mutual defence arrangement at the core of the NATO alliance, the U.S.-Japan alliance is built around an asymmetry. The U.S. is obligated to defend Japan, while Japan is obligated to provide bases to the U.S. military, “[f]or the purpose of contributing to the security of Japan and the maintenance of international peace and security in the Far East”.
103
Article VI, Treaty of Mutual Cooperation and Security between Japan and the United States of America, 1960.Hide Footnote  In view of constitutional constraints, Japan is not obligated to defend the U.S., but the 2015 security legislation permits Japan to do so under certain circumstances with Diet approval.

Some defence analysts have long harboured questions about whether the U.S. would put its own cities at risk from Chinese missiles in order to come to Tokyo’s defence. The Trump administration’s “America first” orientation only raises the level of scepticism. But Japan shows no signs of distancing itself from the U.S. Faced with an ascendant China, Tokyo could have sought to turn away from Washington and accommodate Beijing. Instead, Japan has moved to deepen the U.S. alliance, in part by developing its ability to contribute to deterrence.
104
Crisis Group interviews, security experts, Tokyo, August and November 2024; and by telephone, September 2025. See also Shogo Suzuki and Corey Wallace, “Explaining Japan’s Response to Geopolitical Vulnerability”, International Affairs, vol. 94, no. 4 (2018), p. 719.Hide Footnote

During the first Trump administration, Prime Minister Abe assiduously cultivated a personal relationship with the U.S. president, which served to blunt the impact of the latter’s alliance scepticism.
105
Crisis Group interviews, experts, Tokyo, August and October-November 2024; March-April 2025. Abe did so notwithstanding the many “humiliations” to which Trump subjected him, not least the U.S. overtures to North Korea. Paul O’Shea and Sebastian Maslow, “‘Making the Alliance Even Greater’: (Mis-)managing U.S.-Japan Relations in the Age of Trump”, Asian Security, vol. 27, no. 2 (2021), pp. 203-205.Hide Footnote  President Joe Biden made strengthening alliances a theme of his foreign policy and worked with Japan and other allies to build deterrence.
106
 James L. Schoff, “Modernizing US-Japan Command and Control Relationships for New Challenges”, NEXT Alliance Conference summary, May 2023, p. 7.Hide Footnote  The capstone of the Biden administration’s work on bolstering the alliance was a pledge to upgrade the U.S. Forces Japan to a joint force headquarters that would serve as a counterpart to the JJOC.
107
Hirohito Ogi, “Beyond Policy Limits: Rethinking U.S.-Japan Command and Control”, Stimson Center, 14 March 2025.Hide Footnote  This step is important because it will enable a much-needed higher level of coordination between U.S. and Japanese forces amid increasing regional threats and Japan’s military transformation, especially its acquisition of long-range missiles. In July 2024, then-Defense Secretary Lloyd Austin described the upgrade as “the most significant change to U.S. Forces Japan since its creation”.
108
C. Todd Lopez, “U.S. intends to reconstitute U.S. Forces Japan as Joint Forces Headquarters”, U.S. Department of Defense News, 28 July 2024.Hide Footnote

The common metaphor describing the division of labour between Japan and the U.S. is that of “shield and spear”, with Japan (the shield) providing material support for, and defence of, U.S. military assets based in Japan (the spear).
109
Japan hosts larger U.S. forces than any other country, including the U.S. Seventh Fleet, the only forward-stationed carrier strike group, at Yokosuka on Tokyo Bay, the Fifth Air Force (with bases in Yokota, Misawa and Kadena, Okinawa) as well as the the Marine Corps’ III Marine Expeditionary Force based in Okinawa. Jeffrey W. Hornung, Managing the U.S.-Japan Alliance: An Examination of Structural Linkages in the Security Relationship (Washington, 2017), p. 4.Hide Footnote  With Japan’s acquisition of long-range precision strike missiles, however, that distinction is breaking down.
110
Lionel P. Fatton, “‘Japan is Back’: Autonomy and Balancing Amidst an Unstable China-U.S.-Japan Triangle”, Asia Pacific Policy Studies, no. 5 (2018), p. 265.Hide Footnote  This shift has implications for how the alliance operates, demanding greater integration of command and control, as well as doctrine and planning. Japan’s new military capabilities and broader legal scope for collective self-defence mean that the JSDF and U.S. military need to plan and train to fight together. It is urgent that the parties hold a frank, thorough discussion of roles and responsibilities in the event of a conflict.

The current command-and-control arrangement for U.S. forces in Japan is not optimal for the demands of fighting a war in or around Japan. In contrast to the U.S.-Republic of Korea Combined Forces Command, headed by a U.S. four-star general with operational control of U.S. and South Korean forces that are primed to “fight tonight”, U.S. Forces Japan is led by a three-star general, concurrently commander of the Fifth Air Force based at Yokota, who lacks operational authority over other forces based in Japan.
111
Jeffrey W. Hornung and Zack Cooper, “Shifting the U.S.-Japan Alliance from Coordination to Integration”, War on the Rocks, 2 August 2024.Hide Footnote  This commander’s responsibilities are largely administrative and concerned with political matters pertaining to the U.S. presence in Japan. U.S. forces in Japan report to their respective commanders based at the Indo-Pacific Command in Hawaii, so coordination with the JSDF must be carried out across 6,000km and five time zones.
112
William Gallo, “US, Japan eye alliance upgrades during Biden-Kishida meeting”, VOA, 2 April 2024.Hide Footnote  The distance and time difference are problems, according to alliance managers. A U.S. official said, “In the case of war, there’s a need for authority to deploy U.S. forces and engage with Japanese counterparts in the same time zone, in person if necessary”.
113
Crisis Group interviews, U.S. National Security Council official, Washington, September 2024; security expert, Tokyo, October 2024. The U.S. FY 2023 National Defense Authorization Act mandated establishment of a joint force headquarters in the Indo-Pacific but did not specify where it should be located. Japan is an obvious choice, given the concentration of U.S. forces there, but Guam or Hawaii are also possible locations. 1087(b) of the National Defense Authorization Act for Fiscal Year 2023 (Public Law 117–263; 136 Stat. 2802; 10 U.S.C. 161 note); Mark Montgomery, “A C2 Structure for a Strong U.S.-Japan Alliance”, Center for Strategic and International Studies, 21 June 2023. Hide Footnote

Japan’s acquisition of long-range missiles makes working together even more imperative. Not only will Japan rely on the U.S. for targeting information and battle-damage assessments in the near term, but both parties will want to avoid friendly fire incidents that could result from inadequate planning, communication and situational awareness. Japan’s possession of long-range missiles also means that control of escalation dynamics, in particular the decisions that could intensify a dispute to the level of armed conflict, will no longer be solely in U.S. hands, underscoring the need for greater coordination between Japanese and U.S. forces.
114
Ogi, “Beyond Policy Limits: Rethinking U.S.-Japan Command and Control”, op. cit.Hide Footnote

While alliance managers on both sides argue for its importance, closer coordination of command and control raises a host of issues that must be resolved. Among these are the different legal systems governing use of force for each country’s armed forces; the slower pace of Japanese decision-making, given the need for Diet approval of most JSDF operations; and U.S. reluctance to share intelligence, due to concerns about Japan’s procedures for handling classified information.
115
Crisis Group interviews, defense official, Tokyo, August 2024, security experts, Tokyo, November 2024. See also Schoff, “Modernizing US-Japan Command and Control Relationships for New Challenges”, op. cit., pp. 8-10; “Diet panel seeks improvement over MSDF info mishandling”, Yomiuri Shimbun, 18 July 2024.Hide Footnote

It is not yet clear how the new U.S. headquarters will be configured or what the scope of its authority will be.
116
Crisis Group interviews, security experts, September 2025. Media reports in March indicated that the Pentagon was shelving plans to upgrade U.S. Forces Japan, though Hegseth, during his visit to Tokyo, insisted that Washington was proceeding with establishing a joint force command focused on “warfighting”. “Pentagon weighs canceling U.S. Forces Japan upgrade: Reports”, Nikkei Asia, 20 March 2025; “Hegseth says US is upgrading Japan ops to war-fighting command”, Bloomberg, 30 March 2025.Hide Footnote  Japan’s constitutional constraints on the use of force preclude a combined command along the lines of U.S. forces in South Korea. In March, the U.S. launched the team that will coordinate with the new JJOC, but as of November it appears to have made no determination as to how the new joint force headquarters will be structured.
117
“Coordination office marks first step in U.S. Forces Japan’s shift to ‘warfighting’ command”, Japan Times, 31 July 2025.Hide Footnote

Bureaucratic interests will likely play a role in shaping the new command, as the Indo-Pacific Command may be reluctant to delegate authority. Many Japanese experts wish to see the U.S. joint force in Japan headed by a four-star general or admiral to ease coordination with the JJOC’s four-star leader, though this arrangement could complicate existing U.S. chains of command.
118
Crisis Group correspondence, defence expert, October 2025; retired Japanese admiral, November 2025.Hide Footnote  Those experts would argue (with good reason) that the effectiveness of combined Japan-U.S. operations in a future conflict, and therefore of allied deterrence, hinges on devising a command-and-control structure that responds to the growing threats in the region, meets the increasing technological demands of cross-domain warfare and accounts for Japan’s introduction of new military capabilities.

The importance of developing a stronger understanding between Tokyo and Washington about roles and responsibilities in the event of a conflict in the Indo-Pacific is most clearly illustrated by the prospect of war across the Taiwan Strait. Japan’s response to a Chinese blockade or invasion of Taiwan would depend on the nature of Beijing’s offensive and how the Japanese government classifies the contingency.
119
If China were to attack U.S. bases in Japan or attempt to take the Senkaku Islands as part of a Taiwan invasion, Japan could use force in self-defence. Short of such an attack, the Japanese government could classify a war over Taiwan as a situation that has “an important influence on Japan’s peace and security”. Such a situation, if left unaddressed, could lead to an attack on Japan. Alternatively, Tokyo could classify an invasion of Taiwan as a “survival-threatening situation”, in which an armed attack on a foreign country that is in a close relationship with Japan occurs, which in turn poses a threat to Japan’s survival. In an “important influence situation”, Japan could provide logistical and other support to U.S. and partner military forces outside active combat zones. In a “survival-threatening situation”, Japan could use military force as an exercise of its right to collective self-defence. Mirna Galic, “Japan’s authorities in a Taiwan contingency: Providing needed clarity”, War on the Rocks, 6 October 2021; Takahashi Kosuke, “How would Japan respond to a Taiwan contingency?”, The Diplomat, 2o August 2022.Hide Footnote  In any event, the U.S. will not be able to defend Taiwan without use of its bases in Japan, which means that prior consultation with Tokyo is essential.
120
Davd Sacks, “Enhancing U.S.-Japan Coordination for a Taiwan Conflict”, Council on Foreign Relations, January 2022, p. 15; Mark F. Cancian, Matthew Cancian and Eric Heginbotham, “The First Battle of the Next War: Wargaming a Chinese Invasion of Taiwan”, Center for Strategic and International Studies, January 2023, pp. 57-59.Hide Footnote  Given the variety and scope of potential JSDF contributions, including logistical support in non-combat areas, defence of Japan’s airspace and denial of key Japanese straits to Chinese ships, allied military planners have their work cut out.

Under the second Trump administration, the Pentagon has reportedly pressed Japanese and Australian defence officials to commit to defending Taiwan, even as the U.S. adheres to a policy of strategic ambiguity.
121
“US demands to know what allies would do in event of war over Taiwan”, Financial Times, 12 July 2025.Hide Footnote  As demonstrated by the mid-November dustup between Tokyo and Beijing over Japan’s potential role in Taiwan’s defence, the issue could hardly be more sensitive from China’s perspective. Japan’s response to a cross-strait war would be conditioned by myriad factors depending on the specific circumstances of such a conflict.
122
Adam P. Liff, “The U.S.-Japan Alliance and Taiwan”, Asia Policy, vol. 17, no. 3 (July 2022), p. 132.Hide Footnote  

Since President Donald Trump’s return to the White House, the trust underpinning the U.S.-Japan alliance is coming under greater strain, with Tokyo receiving both positive and negative signals from Washington. Trump’s first summit with then-Japanese Prime Minister Shigeru Ishiba in February went smoothly, and their joint statement hit upon familiar themes, including trilateral cooperation with allies and the Quad, as the grouping of Australia, India, Japan and the U.S. is known.
123
“United States-Japan Joint Leaders’ Statement”, White House, 7 February 2025.Hide Footnote  U.S. Secretary of Defense Pete Hegseth visited Japan in late March and offered reassurances about the U.S. commitment.
124
“Hegseth says US is upgrading Japan ops to war-fighting command”, op. cit.Hide Footnote

But tensions soon surfaced. Trump criticised the alliance in March, alleging that it represents an “interesting deal” from which Japan makes “a fortune”.
125
“Trump calls Japan-U.S. alliance an ‘interesting deal’”, Reuters, 7 March 2025.Hide Footnote  Trump’s undersecretary of defense for policy, Elbridge Colby, has repeatedly called upon Japan to increase its defence spending to 3 per cent of GDP, and reportedly privately pushed Tokyo for 3.5 per cent.
126
“Advance Policy Questions for Elbridge Colby, Nominee for Appointment to be Under Secretary of Defense for Policy”, U.S. Senate Armed Services Committee, 2025; “Japan faces an era-defining reset with the US”, Financial Times, 14 July 2025.Hide Footnote  The administration’s approach to Ukraine, especially President Volodymyr Zelenskyy’s rough treatment by Trump at the White House in February, shocked decision-makers in Tokyo.
127
Crisis Group interviews, officials and security experts, Tokyo, March-April 2025.Hide Footnote  Some analysts in Tokyo are concerned that the U.S. may seek a grand bargain with China over Taiwan, in which Trump signals indifference to Taiwan’s fate in exchange for economic benefits from China, that would leave Japan out in the cold.
128
Crisis Group interviews, security analysts, Tokyo, March-April 2025. Crisis Group Report, Asia in Flux, op. cit., p. 24.Hide Footnote  Noting U.S. naval deployments to the Red Sea and Middle East, a Japanese analyst concluded that the present team in the White House “doesn’t really care about Asia”.
129
Crisis Group interview, security analyst, Tokyo, 27 March 2025. This interview took place before the highly publicised U.S. naval buildup in the Caribbean Sea.Hide Footnote

Trump’s threats of steep tariffs on Japan, announced on 2 April, and subsequent trade talks further strained ties. A deal was reached on 22 July, but the months of negotiations were bruising. Trump called Japan “spoiled”; Ishiba labelled the prospect of U.S. tariffs a “national crisis”.
130
“Japan regrets Trump’s tariff, aims for deal by new Aug. 1 deadline”, Kyodo News, 8 July 2025; “Japan digs deep to address ‘national crisis’ caused by Trump tariffs”, Japan Times, 4 April 2025.Hide Footnote  Liberal Democratic Party policy chief Itsunori Onodera said “these reciprocal tariffs are a problem that has shaken international economic affairs to their very foundation”, using the same language the National Security Strategy used to describe the blow to the international order dealt by Russia’s all-out invasion of Ukraine.
131
Tobias Harris, “Japan’s ‘Zelenskyy moment’”, Observing Japan, 8 April 2025.Hide Footnote  In June, Tokyo took the extraordinary step of postponing ministerial-level security talks, scheduled for 1 July, reportedly after the U.S. asked Japan to raise defence spending.
132
 “U.S. calls Japan’s defense spending ‘manifestly inadequate’”, Asahi Shimbun, 5 September 2025.Hide Footnote  An April poll found that 77 per cent of respondents did not believe the U.S. would protect Japan in an emergency.
133
“Survey: 77% doubt U.S. will protect Japan in military crisis”, Asahi Shimbun, 28 April 2025. The newspaper conducted a nationwide mail survey of 3,000 voters and got a 63 per cent response rate.Hide Footnote

Japan is increasingly concerned about the credibility of U.S. extended deterrence, or the “nuclear umbrella”, given events playing out in Europe and Asia, as well as in U.S. politics.
134
Crisis Group interviews, security experts, Tokyo, October-November 2024.Hide Footnote  Some analysts note the Pentagon projections that China will have 1,000 operational nuclear warheads by 2030, extrapolating from this number parity with the U.S. stockpile by 2035, which they say diminishes the credibility of U.S. extended deterrence.
135
Crisis Group interviews, former officials and senior officers, Tokyo, November 2024; March 2025. See “Annual Report to Congress: Military and Security Developments Involving the People’s Republic of China 2024”, U.S. Department of Defense, pp. 101, 109.Hide Footnote  Other nuclear weapons experts describe assessments that China will be a “near peer” of the U.S. in the near future as a “gross exaggeration”.
136
“Even the worst-case 2023 projection of 1,500 warheads by 2035 amounts to less than half of the current U.S. nuclear stockpile”. Hans M. Kristensen et al., “Chinese Nuclear Weapons, 2025”, Bulletin of the Atomic Scientists, vol. 81, no. 2 (2025), p. 140.Hide Footnote  Nonetheless, the notion that it might be is stimulating discussions in Tokyo about the need to expand dialogue with Washington, including the possibility of introducing U.S. nuclear weapons into Japan, akin to NATO-style nuclear sharing, and of deploying them from Japanese aircraft or ships.
137
Crisis Group interviews, security experts, Tokyo, November 2024; March-April 2025. Japanese forces could launch tactical nuclear weapons stored outside Japan, in Guam, for example. Eric Heginbotham and Richard J. Samuels, “Vulnerable U.S. Alliances in Northeast Asia: The Nuclear Implications”, The Washington Quarterly, vol. 44, no. 1 (2021), pp. 170-171.Hide Footnote There is also renewed discussion of the still-remote possibility of Japan developing its own nuclear deterrent (see Section V.B. below).

Sanae Takaichi, a protégée of the late Prime Minister Abe and a conservative hawk, became prime minister on 21 October after winning an election to head the Liberal Democratic Party and quickly affirmed plans to accelerate Japan’s defence transformation. She declared that Japan would reach its target of 2 per cent of GDP spending on defence ahead of schedule and expand Japan’s arms exports.
138
“Japan’s Sanae Takaichi steps up defence spending ahead of visit by Donald Trump”, Financial Times, 24 October 2025; “Japan’s Takaichi to push defense exports on back of high approval rating”, Nikkei Asia, 28 October 2025.Hide Footnote  Her first summit with President Trump, just one week after she took office, focused on economic matters but offered the opportunity for both leaders to affirm the strength of the alliance and set a cooperative tone for bilateral ties.
139
“Donald Trump says US relationship with Japan ‘at strongest level’”, Financial Times, 27 October 2025.Hide Footnote  Secretary Hegseth also visited Japan in October and, in a joint press conference with his Japanese counterpart, said, “We have nothing but the utmost respect for the … investment in the Japanese military and the pace at which they undertake it”.
140
“Hegseth says U.S. never demanded Japan defense spending hike”, Japan Times, 29 October 2025.Hide Footnote  Despite these positive signals, Tokyo is reportedly disappointed that the Trump administration has not offered it greater public support in the dispute with China over Takaichi’s remarks about Taiwan.
141
“Japan frustrated at Trump administration’s silence over row with China”, Financial Times, 7 December 2025.Hide Footnote

To hedge against U.S. retrenchment, Tokyo has stepped up efforts to build security relationships with other countries, principally U.S. allies, in Asia and beyond. According to a retired flag officer, “We need the help of like-minded countries for our survival and quality of life”.
142
Crisis Group interview, retired Japanese admiral, Tokyo, 5 November 2024.Hide Footnote  From Japan’s perspective, these partnerships are driven by two rationales. First, it is a way of taking some of the burden off the U.S. so that it has help providing security for its traditional partners and allies in Asia.
143
Crisis Group interviews, security experts, Tokyo, August and October 2024.Hide Footnote  Secondly, these non-U.S. partnerships are a means of bolstering and legitimising the Japan-U.S. alliance, what one scholar calls “bilateralism plus”.
144
 Hughes, Japan as a Global Military Power, op. cit., p. 75.Hide Footnote  Japan is an active player in multistate “minilateral” arrangements, with and without the U.S., seeking to strengthen regional deterrence, not least through signalling that Japan is not alone.

Outside the U.S., Australia is Japan’s most important security partner. The relationship is often described as a “quasi-alliance”, underpinned by shared threat perceptions and desire to keep the U.S. engaged in the region.
145
 Crisis Group interview, security expert, Tokyo, 5 November 2024. See also NSS 2022, p. 21; Nanae Baldauff, Japan’s Defense Engagement in the Indo-Pacific (Cham, 2024), p. 63; and H. D. P. Envall and Thomas S. Wilkins, “Japan and Australia: Forging an Indo-Pacific Partnership”, in Buszynski, Handbook of Japanese Security, op. cit., p. 389.Hide Footnote  Australia’s vast land mass offers training grounds that Japan lacks; likewise, its capacity to stockpile ammunition, spare parts and other items would be important for sustaining a protracted fight.
146
Crisis Group interview, security analyst, Tokyo, March 2025.Hide Footnote  Canberra and Tokyo have concluded an Acquisition and Cross-Servicing Agreement, enabling mutual supply of ammunition, and a Reciprocal Access Agreement to let their militaries conduct drills on each other’s territory. In December, the two sides agreed to a Framework for Strategic Defence Coordination to “to ensure effective collaboration at all levels and in all situations from peacetime to contingencies”.
147
“Japan-Australia Defense Ministers’ Joint Statement – Establishment of the Framework for Strategic Defence Coordination”, press release, Japanese Ministry of Defense, 7 December 2025.Hide Footnote

Japan’s ties with the Philippines are tightening rapidly as Manila shifts from its traditional focus on internal security to external threats, in large measure due to the other island nation’s location in the first island chain near Taiwan and the South China Sea.
148
 Crisis Group interview, security expert, Tokyo, November 2024. Crisis Group Report, Riding Unruly Waves, op. cit.Hide Footnote  In April, Prime Minister Ishiba described Japan and the Philippines as “almost like allies”.
149
“‘Almost like allies’: Tokyo and Manila eye two more defense pacts”, Japan Times, 30 April 2025.Hide Footnote

Tokyo’s relations with South Korea, long strained by divergent views of the history of Japan’s colonial rule of the peninsula from 1910-1945 and unresolved territorial issues, improved with the Biden administration’s efforts to foster rapprochement.
150
The two countries also have a territorial dispute over South Korean-controlled islets in the Sea of Japan.Hide Footnote  Domestic politics in either country could reverse the thaw, but concerns in both Seoul and Tokyo about U.S. reliability appear for the moment to be drawing the two governments together.
151
Crisis Group interview, security expert, September 2025.Hide Footnote

Japan has cultivated ties with India, including through the Quadrilateral Security Dialogue, as a prospective counterweight to China. Some Japanese analysts want Tokyo to persuade New Delhi to play a more active role in security east of the Malacca Straits, while others argue that Japan needs to have a more thorough discussion about what Tokyo can realistically expect of Indian contributions to the provision of public goods, including security, in the Indo-Pacific.
152
Crisis Group interviews, retired Japanese admiral, Tokyo, 5 November 2024; security expert, Tokyo, April 2025.Hide Footnote

Looking to South East Asia, Japan has been an important economic partner for countries in the region for half a century and, over the past decade, it has developed security relationships in the region, principally through capacity building. Though sometimes frustrated by regional states’ tendency to placate Beijing, Tokyo recognises the centrality of the Association of South East Asian Nations’ multilateral architecture.
153
Crisis Group interviews, officials and experts, Tokyo, August and November 2024.Hide Footnote  South East Asian states have been priority recipients of Japan’s Official Development Assistance and, since 2023, Official Security Assistance, signalling Japan’s growing role as a regional security actor.
154
Crisis Group interview, foreign ministry official, Tokyo, March 2025.Hide Footnote

Farther afield, Japan’s defence relationships with the EU, NATO and their member states are burgeoning. For Tokyo, the EU represents a collection of generally like-minded countries that, for the most part, are committed to what Japan and the bloc call a “free and open international order based on the rule of law”.
155
“Security and Defence Partnership between the European Union and Japan”, 1 November 2024.Hide Footnote  In November 2024, the EU and Japan signed a Security and Defence Partnership agreement that, though largely aspirational, is symbolic of perceptions in Tokyo and European capitals of interdependence between Indo-Pacific and European security, as exemplified by cooperation among China, North Korea and Russia.
156
Paul O’Shea, “EU-Japan security partnership shows promise but lacks action”, East Asia Forum, 28 December 2024.Hide Footnote  Japan also sees an opportunity for arms exports as Europe ramps up spending.
157
Lionel Laurent and Gearoid Reidy, “The security alliance the world needs now”, Bloomberg (editorial), 26 March 2025.Hide Footnote

There are still other dimensions to Japan’s broadening partnerships in Europe. Japan is cooperating with the UK and Italy on the Global Combat Air Program, a next-generation fighter and the first such project for Tokyo with partners other than the U.S.
158
Crisis Group interview, Japanese Ministry of Defense official, Tokyo, August 2024.Hide Footnote  Japan’s Reciprocal Access Agreement with the UK, signed in 2023, was its second after the accord with Australia. Kishida was the first Japanese prime minister to attend a NATO summit, in June 2022, and Tokyo appointed an ambassador to the alliance in January.
159
 Paul O’Shea and Sebastian Maslow, “Rethinking Change in Japan’s Security Policy: Punctuated Equilibrium Theory and Japan’s Response to the Russian Invasion of Ukraine”, Policy Studies, vol. 45, nos. 3-4 (2024), p. 653; “NATO chief makes Japan debut with focus on defense industry tie-ups”, Japan Times, 8 April 2025.Hide Footnote

In the face of deepening scepticism about the durability of the U.S. alliance, Tokyo’s network of partnerships may appear to be a hedge against abandonment. As an analyst put it, “If any contingency arises here we need to rely on partners, especially when the U.S. commitment is more doubtful than we’ve seen before”.
160
Crisis Group interview, security expert, Tokyo, 1 April 2025.Hide Footnote  To be sure, any significant payoff in greater strategic autonomy from the U.S. is a distant prospect.
161
Crisis Group interview, analyst, Tokyo, April 2025.Hide Footnote  But investing in diversification could have over-the-horizon benefits; meanwhile, in the near term, Japan and its partners may benefit from working together on projects like defence production, especially of munitions, that would be crucial to success in a protracted war.
162
Crisis Group interviews, retired Japanese admiral, Tokyo, 1 November 2024; security expert, September 2025.Hide Footnote

Japan has moved with determination to pursue the defence priorities set out in the 2022 strategic documents. But it faces major hurdles to realising its ambition to shoulder a greater share of the burden of its own defence and play a more active role in supporting a free and open order in the Indo-Pacific. These efforts are complicated by the shifting balance of power in the region, fiscal and demographic limitations, and constitutional constraints on the use of force.

Japan’s departure from pacifist norms is based on a broad political consensus. These principles retain adherents, especially among older Japanese, and remain a constraint on the pace and scale of Japan’s military modernisation. The Liberal Democratic Party has governed Japan for all but six years since its founding in 1955, and, though the party is a big tent, its leaders are generally conservative. They tend to support military modernisation and the U.S. alliance. The main opposition parties also favour increased defence spending, and no change in government is likely to precipitate drastic policy shifts.
163
Crisis Group interviews, experts and officials, Tokyo and Washington, August-October 2024.Hide Footnote

China’s growing military might and assertiveness in its neighbourhood have contributed to the Japanese public’s re-evaluation of national defence. The Peace and Security Laws in 2015 ignited huge protests, but in 2022 the three documents prompted no such show of disapproval.
164
Crisis Group interviews, security experts, Tokyo, August 2024.Hide Footnote  Beyond the friction in the Senkaku/Diaoyu Islands, China’s launch of ballistic missiles into Japan’s contiguous zone, near its territorial waters, in August 2022 “shocked” many Japanese, in the words of a retired flag officer.
165
Crisis Group interview, retired Japanese admiral, Tokyo, 5 November 2024.Hide Footnote  Anti-China sentiment is running high.
166
Crisis Group interview, academic, Tokyo, August 2024.Hide Footnote  Russia’s all-out invasion of Ukraine also boosted public support for increased military spending.
167
Crisis Group interview, security experts, Tokyo, August 2024; March 2025.Hide Footnote  As a Japanese official put it, war in Ukraine helped convince many Japanese that “peace has its conditions”.
168
 Crisis Group interview, foreign ministry official, Tokyo, November 2024.Hide Footnote

Realisation of defence ambitions remains contingent on annual budgets. In 2022, the Kishida government committed to hiking total defence spending to 43.5 trillion yen, roughly $300 billion, over five years, a 56 per cent rise over the previous plan.
169
Adam P. Liff, “No, Japan is not planning to ‘double its defense budget’”, Brookings Institution, 22 May 2023.Hide Footnote  Japan has also pledged to spend 2 per cent of GDP on defence by 2027; the fiscal 2025 budget is equivalent to 1.8 per cent of GDP.
170
“Japan to spend 1.8% of GDP on defense in 2025, 2% target in sight”, Kyodo News, 15 April 2025.Hide Footnote  While the increase is dramatic, the 2 per cent goal includes outlays in categories not previously incorporated into defence spending, including the coast guard and research and development.
171
Heginbotham et al., “Pushing on an Open Door”, op. cit., p. 51.Hide Footnote  Moreover, yen depreciation is squeezing procurement.
172
“Japan defense spending goals hit by inflation, weak yen and political uncertainty”, Japan Times, 29 December 2024.Hide Footnote  Japan’s increased spending falls well short of the 5 per cent of GDP that the Pentagon has proposed as a “global standard”, but few analysts believe that even 2.5 per cent is politically achievable given the country’s fiscal constraints.
173
Crisis Group interviews, defence experts, September-October 2025. “Pentagon says Japan must meet ‘global standard’ and spend 5% of GDP on defense”, Japan Times, 20 June 2025.Hide Footnote

Thus far, the government has made good on plans for increased spending, but how to pay for it is contentious. The government is reluctant to raise its debt ceiling for continuing expenses, but the alternative of higher taxes would be politically costly and could have deleterious consequences for the economy.
174
Crisis Group interviews, security and foreign policy experts, August and November 2024; March-April 2025.Hide Footnote  The governing coalition has plans to raise more than one trillion yen of the planned defence spending through corporate and tobacco taxes, starting in April 2026, and income taxes, the timing of which has not been decided.
175
“Parties divided on defense spending increase”, Jiji, 10 July 2025.Hide Footnote

Perhaps the hardest constraint on Japan’s remilitarisation is demographic. In 2005, Japan became the first major power to reach “super-aged” status, in which 20 per cent or more of the population is 65 or older. Its population is also shrinking.
176
Andrew Oros, “Japan’s Paradoxical Demographic Decline and Defense Rise: Expanding Security Concerns and Security Roles”, in Zhiqun Zhu, ed., Japan’s Paradoxical Demographic Decline and Defense Rise: Expanding Security Concerns and Security Roles (Singapore, 2025), p. 56.Hide Footnote  The JSDF has routinely failed to meet its recruiting quotas for the all-volunteer military, and prospects of that changing are slim. In fiscal 2023, the JSDF signed up 9,959 new members, the lowest figure ever and only 51 per cent of its goal.
177
“Japan Self-Defense Forces miss recruitment goal by half”, Nikkei Asia, 9 July 2024.Hide Footnote  Moreover, the problem of a declining pool of potential recruits will only grow worse. Japan will need to enlist more than 1 per cent of its population to meet recruitment targets over the next decade.
178
 Tom Le, “The Japanese Military Has a People Problem”, Foreign Affairs, 28 March 2025.Hide Footnote

Compounding the demographic slump is the reluctance of many to choose a military career. Many parents remain wary of encouraging their children to serve in the military, due to the limited prospects for advancement and perceived poor quality of life for service members.
179
Crisis Group interview, security expert, Tokyo, October 2024.Hide Footnote While the JSDF’s public image has improved over the past twenty years, thanks largely to its disaster relief role, more remunerative, comfortable jobs are available, and military service continues to lack prestige.
180
Crisis Group interviews, security experts, Tokyo, August and October 2024.Hide Footnote

The 2022 National Defense Buildup Program cites a variety of measures to address the problem, including raising the retirement age and improving living and working conditions.
181
 “Defense Buildup Program 2022”, op. cit., p. 5.Hide Footnote  The JSDF has upgraded facilities for women service members and, as of 2018, has women submarine crews. In July, the Ministry of Defense lifted all remaining restrictions on military roles for women. It has achieved its previous goal of having 9 per cent women in the ranks and is now aiming to have 12 per cent by 2030.
182
Oros, “Demographic Decline”, op. cit., p. 67; “Japan removes last restrictions on female soldiers”, Defence Blog, 18 July 2025; “Japan wants a stronger military. Can it find enough troops?”, The New York Times, 13 December 2023.Hide Footnote  But the JSDF struggles with retention.
183
 Crisis Group interview, security expert, Tokyo, October 2024.Hide Footnote

The challenge of Japan’s demographic slump extends beyond military recruitment to Japan’s bureaucracy and arms industries. The Ministry of Defense lacks sufficient staff to handle contracts for procurement, leading to delays.
184
Crisis Group interviews, security experts, Tokyo, August and November 2024.Hide Footnote  Likewise, Japan’s defence contractors do not have enough engineers to design and build the software and hardware specified in the government’s expansion plans.
185
Crisis Group interview, defense expert, Tokyo, 9 August 2024.Hide Footnote

Japanese analysts often describe Japan’s options in the face of geopolitical challenges, the shifting balance of power and its own limitations in terms of alphabetically designated “plans”. Thus, with minor variations, Plan A is a deeper alliance with the U.S., but a U.S. that is committed to maintaining a forward presence in Asia and defending the rules-based international order. Plan B would constitute pursuit of strategic autonomy to cope with U.S. retrenchment, including development of a nuclear arsenal. Plan C, which has few proponents, means acquiescing to Japan’s subordination in a regional order dominated by China.
186
Crisis Group interviews, security experts, Tokyo, August and November 2024; March-April 2025.Hide Footnote  Some analysts call Japan’s current approach “Plan A+”, that is, maintaining the U.S. alliance to the extent possible, while also expanding defence partnerships and developing its own conventional defence capabilities. But they know that this course of action could not replace the U.S. role should Washington decide to scale it back.
187
 Heginbotham and Samuels, “Vulnerable U.S. Alliances in Northeast Asia”, op. cit., p. 162.Hide Footnote

The second Trump administration is deepening worries among Japanese strategists about alignment of the two countries’ interests. While the U.S. has always tolerated double standards for its friends, and stretched international law for its own benefit, President Trump has gone further than any president since the Cold War in calling U.S. support for the international order into question. Trump’s treatment of allies, his disregard for international law (evident in his musings about the conquest of Greenland and parts of Panama) and his admiration for strongmen are all but irreconcilable with the principles underlying Japanese foreign policy since World War II. Many thus feel that U.S. assurances to Tokyo ring hollow.
188
Crisis Group Report, Asia in Flux, op. cit., pp. 21-24.Hide Footnote

Two broad responses to this dawning reality are evident. The first is to stick with Plan A in view of the inadequacy of Japan’s own military and that of its partners to fill the void that would be left by the U.S. Inertia is a factor, but so, too, is cold calculation. As one analyst said, “This is the least expensive and most realistic option”.
189
Crisis Group interview, security analyst, September 2025.Hide Footnote  The second response is to contemplate strategic autonomy, which begins with a “psychological process” of recognising that Japan’s security is in the hands of a capricious ally.
190
Ibid.Hide Footnote  Another analyst said, “Japan needs to look at policy for after the U.S. has retrenched to Guam and Hawaii”.
191
Crisis Group interview, security analyst, Tokyo, March 2025.Hide Footnote  In September, an expert panel recommended that Japan “strengthen domestic production systems for essential equipment” and introduce “state-owned arsenals”, both steps toward greater independence.
192
“Summary of Recommendations from the ‘Expert Panel on Fundamental Reinforcement of Defense Capabilities’”, 19 September 2025.Hide Footnote

For some, strategic autonomy means developing nuclear weapons. Japan’s policy toward these weapons has been based since 1967 on the “three non-nuclear principles”: not to build or deploy nuclear weapons or introduce them into the country.
193
 Declassified documents reveal that the third principle was frequently violated by allowing U.S. ships carrying nuclear weapons into Japanese ports under cover of Washington’s “neither confirm nor deny” policy. Crisis Group Report, Japan and North Korea: Bones of Contention, op. cit., p. 22.Hide Footnote  Japan has periodically studied the option of acquiring nuclear weapons, only to dismiss it every time.
194
 Llewelyn Hughes, “Why Japan Will Not Go Nuclear (Yet): International and Domestic Constraints on the Nuclearization of Japan”, International Security, vol. 31, no. 4 (Spring 2007), p. 76.Hide Footnote  Yet leaders and strategists are increasingly broaching the subject again, especially since Russia began using nuclear threats to intimidate NATO over Ukraine.
195
Yuki Tatsumi, “How Russia’s Invasion of Ukraine Changed Japan’s Approach to National Security”, Stimson Center, 16 February 2023.Hide Footnote  Already in 2022, former Prime Minister Abe said, “Debate over the reality of how the world’s security is protected must not be considered a taboo” in reference to the prospect of the U.S. deploying nuclear weapons to Japan.
196
“Nuclear sharing, a taboo or unavoidable reality? Japan parties intensify debate”, Mainichi Shimbun, 2 March 2022.Hide Footnote  While then-Prime Minister Kishida quashed the idea, reluctance to discuss nuclear weapons is eroding. Prime Minister Takaichi has indicated that her government may review the prohibition on introducing these weapons into Japan.
197
“Takaichi sidesteps commitment to decades-old non-nuclear principles”, Japan Times, 12 November 2025.Hide Footnote

Japanese analysts are largely sceptical of the wisdom of acquiring nuclear weapons, though it is well within the country’s technical capacity.
198
Japan possesses plutonium, and it has built re-entry vehicles, but it has not manufactured warheads. Crisis Group interview, security expert, Tokyo, 1 April 2025.Hide Footnote  The costs in money and personnel would be high, and conventional priorities would suffer.
199
Crisis Group interviews, security experts, Tokyo, March-April 2025.Hide Footnote  Japan lacks land mass and strategic depth. The entire country is exposed to attack, which militates against a nuclear posture due to increased vulnerability to a first strike and the risk of high civilian casualties; it would need new submarines as launch platforms, driving up the expense further. Were it to seek nuclear weapons, Tokyo would alarm its adversaries, exacerbating the security dilemma. Public opinion remains firmly opposed to nuclear weapons.
200
Crisis Group interview, security experts, Tokyo, April 2025.Hide Footnote  If South Korea were to acquire nuclear weapons, analysts say, these impediments would diminishbecause Japan’s status as the only non-nuclear armed country in North East Asia could be destabilising, but short of the U.S. withdrawing its forces from Japan, Tokyo is likely to focus on developing conventional deterrence.
201
Crisis Group interview, security experts, Tokyo, March, April 2025; Crisis Group correspondence, retired Japanese admiral, November 2025. See also Michael J. Green, Line of Advantage: Japan’s Grand Strategy in the Era of Abe Shinzō (New York, 2022), p. 210.Hide Footnote

Japan’s alliance with the U.S. and its efforts to build up its military capabilities are rooted in the logic of deterrence as the best available means of avoiding war. Tokyo’s assessment of the threats posed by China, Russia and North Korea is driving the transformation of Japan’s security posture and closer cooperation with like-minded partners. The aim of these changes is to redress what Tokyo perceives as an increasingly unfavourable balance of power in the Indo-Pacific. Japan has made significant strides in these efforts over the past decade despite considerable constraints.

But there are further steps that could help Japan bolster its defences and strengthen the regional security architecture, enhancing the alliance and Japan’s own deterrence capability.

One set of issues facing Japan’s efforts to reinforce its capabilities relate to what some analysts refer to as mindset, namely a reluctance to embrace warfighting.
202
Crisis Group interview, defence analyst, Tokyo, 28 October 2024. See also “Is Japan’s military fit for purpose?”, Financial Times, 5 May 2023.Hide Footnote  According to a defence official, “We have weapons, but mentally we are always seeking peace. It’s hard to reject that ideal”.
203
Crisis Group interview, Japanese Ministry of Defense official, Tokyo, August 2024.Hide Footnote  A U.S. official observed a Japanese tendency to “think of deterrence as possessing a capability, but that’s not even half of it. There’s also the willingness to use it and messaging that you’re willing to use it”.
204
Crisis Group interview, U.S. Department of Defense official, Washington, September 2024.Hide Footnote  This problem is compounded by a lack of realistic training, especially involving joint operations.
205
Crisis Group interview, retired U.S. military officer, February 2025. See also Heino Klinck, “Japan’s Defense Priorities and Implications for the U.S.-Japan Alliance”, CSIS, 23 June 2023.Hide Footnote

Secondly, a fundamental problem for Japan is insufficient institutional analytical capacity to determine what is needed to meet strategic objectives.
206
Heginbotham and Samuels, “Active Denial”, op. cit., p. 162.Hide Footnote  The 2022 National Defense Strategy states that “Japan first needs to identify functions and capabilities necessary for national defence … and then determine how those capabilities should be distributed”.
207
“National Defense Strategy 2022”, op. cit., p. 12.Hide Footnote  According to an analyst, “Japan doesn’t have a system to assess what equipment is necessary”; instead, it enlists U.S. think-tanks to help make such judgments.
208
Crisis Group interview, defense analyst, Tokyo, March 2025.Hide Footnote  A retired U.S. military officer with long experience in Japan said the Japanese “just don’t know what to do”, despite their desire to improve their military capabilities.
209
Crisis Group interview, February 2025.Hide Footnote

One consequence is a tendency to make acquisitions based on symbolic value rather than dispassionate analysis of requirements to execute strategy. For revisionist hawks, military hardware has often been a symbol of Japan’s return to “normal” nation status. Long-range missiles are arguably a case in point, as they communicate resolve and have deterrent value, but detractors point to opportunity costs.
210
Crisis Group interviews, security experts, Tokyo, August 2024; September 2025.Hide Footnote  The government and strategists should invest in and promote greater indigenous analytic capability by sponsoring research, training courses and exchange with partners, including on nuclear deterrence.

Thirdly, planning could use a boost. Prime Minister Takaichi intends to expedite formulation of new national security and defence buildup strategies, which offer an opportunity to refine Japan’s priorities.
211
“Japan’s ruling LDP to begin talks on revising security documents next week”, Mainichi, 13 November 2025.Hide Footnote  The new strategies should provide a plan for enhancing stockpiling, maintenance, fuel storage, ammunition and, especially, air base hardening – some of which were overlooked in the past.
212
Crisis Group interviews, defence experts, September-October 2025. See also Heginbotham et al., “Pushing on an Open Door”, op. cit., p. 57.Hide Footnote  A new defence strategy should also address the ground force’s dominance in the force structure, a legacy of the threat of Soviet invasion.
213
Crisis Group interview, analyst, Tokyo, March 2025. See also Heginbotham et al., “Pushing on an Open Door”, op. cit., pp. 58-59; and Hirohito Ogi, “Beyond a Zero-Sum Approach to U.S.-Japan Defense Burden Sharing”, Institute of Geoeconomics, 18 August 2025.Hide Footnote  The Ground Self-Defense Force accounts for roughly two thirds of JSDF personnel, though the potential dangers to Japan today are primarily in the maritime and air domains.
214
 Hinata-Yamaguchi, op. cit., p. 126.Hide Footnote

Likewise, it would be appropriate to update the Guidelines for the Japan-U.S. Defense Cooperation, last revised a decade ago, to more clearly articulate expectations and roles in likely conflict scenarios.
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Crisis Group interviews, defence expert, October 2025; retired Japanese admiral, November 2025. See also Ogi, “Beyond a Zero-Sum Approach to U.S.-Japan Defense Burden Sharing”, op. cit.Hide Footnote  A pragmatic approach would require searching discussions with Washington, an imperative for effective alliance management.

Fourthly, to mitigate its recruiting and retention shortfalls, the government will have to follow through on pledges to improve quality of life for service members and, above all, raise salaries.
216
Crisis Group interviews, security experts, Tokyo, August and October 2024; March-April 2025.Hide Footnote  The Ministry of Defense is also leveraging automation, robotics and artificial intelligence to reduce personnel demands, even if the uncrewed systems are not a remedy for a shortage of troops.
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Crisis Group interviews, security experts, Tokyo, August and October 2024; March-April 2025; and by telephone, October 2025.Hide Footnote  

Fifthly, while Tokyo enhances its capacity to defend itself and deter adventurism, it should guard against actions that might needlessly antagonise China. A case in point is Prime Minister Takaichi’s comment in the Diet that a Chinese blockade of Taiwan could constitute a “survival-threatening situation” according to the 2015 security legislation permitting the exercise of the right of collective self-defence. While the prime minister was arguably stating a point of fact, previous premiers had steered clear of such language to avoid provoking Beijing.
218
“Japan’s Takaichi wades into Taiwan issue, breaking with past governments”, Nikkei Asia, 9 November 2025.Hide Footnote  Takaichi’s remarks appear to have been unscripted, but she has refused to retract them as Beijing has demanded, stating that Japan’s policy toward Taiwan is unchanged. The vociferousness of China’s condemnation of Takaichi, even as Japan has sought to lower the temperature, indicates the most serious diplomatic rift between the two neighbours since the Senkaku/Diaoyu dispute in 2012.
219
“Top Chinese diplomat weighs in on Takaichi’s ‘shocking’ Taiwan remarks”, Japan Times, 23 November 2025; “Japan-China divide widens as fears of long-lasting chill in ties grow”, Japan Times, 24 November 2025. On the Senkaku/Diaoyu dispute, see Crisis Group Report, Dangerous Waters: China-Japan Relations on the Rocks, op. cit.Hide Footnote

To deter without provocation requires functional channels of communication at the working level as well as between senior leaders in Tokyo and Beijing.
220
Crisis Group interview, government adviser, Tokyo, November 2024.Hide Footnote  A hotline established in 2023 between Japanese and Chinese defence authorities has not been used, even as unplanned military encounters proliferate.
221
“Japan-China defense hotline used 1 time for ceremonial call”, Asahi Shimbun, 18 August 2025.Hide Footnote  The two countries should ensure that the hotline functions as a viable crisis management tool. It is worth remembering that Abe, who is credited with galvanising Japan’s remilitarisation, worked to improve ties with Beijing.
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Crisis Group interview, international relations expert, Tokyo, August 2024.Hide Footnote  As tensions over Taiwan increase, such efforts are increasingly necessary to convey intentions and red lines.

Finally, Japan’s relationship with the U.S. requires careful management amid equivocal signals from Washington. The current five-year status of forces agreement runs until March 2027, before which Japan’s contribution to funding U.S. bases in Japan will be renegotiated. Rather than fixate on a percentage figure for defence spending, the two allies should focus what they can do together to deter adventurism and prevent war. Japanese leaders should also encourage progress in clarifying the roles and responsibilities in the event of a conflict in the Indo-Pacific as well as defining command-and-control arrangements in view of the new JJOC and the planned upgrade of U.S. Forces Japan to an operational headquarters.

The Trump administration should appreciate the extent of the anxiety it is instilling in its key Asian ally and manage its trade agenda carefully, keeping its long-term interests in the region front of mind. Policymakers in Washington should be cognisant that their Japanese counterparts are contrasting U.S. assurances to rhetoric and behaviour that is at odds with maintenance of international order, including threats to annex Greenland and Panama.
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Hideshi Tokuchi, “The Japan-U.S. Alliance under New Leadership in Tokyo and Washington, DC”, Sasakawa USA, 2025.Hide Footnote  China will look for any wedge it can drive into the alliance, which could have destabilising repercussions for the balance of power in the region. More broadly, signals of U.S. ambivalence about the security architecture that Washington has underwritten in the post-war era could weaken deterrence and invite adventurism by Beijing, risking either a confrontation with China or a collapse of U.S. credibility.

But Japan should also continue diversifying its partnerships by harnessing the positive momentum it has generated with Indo-Pacific and European partners, diplomatically, strategically and economically. It should expand the scope of joint exercises and sharing of information and defence technology. 

Japan’s sense of vulnerability is increasing, not only because of the growing belligerency and capabilities of its nuclear-armed neighbours, but also because the U.S. appears to be stepping back from its role as pillar of the rules-based international order of which Japan sees itself as both defender and beneficiary. Tokyo has embarked on a program of military modernisation, including the acquisition of a modest offensive capability in the form of long-range precision strike missiles, in part to demonstrate to Washington its readiness to assume greater burdens in establishing deterrence and maintaining a balance of power in the Indo-Pacific. Japan’s effort to build a network of defence partnerships with other U.S. allies and like-minded countries is likewise intended to complement the U.S. alliance and amplify Washington’s influence in Asia, while at the same time making Japan less dependent on the U.S.

Still, for the time being, the U.S. plays a unique and irreplaceable role in Japan’s defence planning. With Washington giving Tokyo greater cause to question the reliability of the alliance, there is likely to be greater debate about the viability of a Plan B to make Japan more self-reliant, including a domestic nuclear deterrent. It remains a remote prospect, but those responsible for Japan’s security must proceed from worst-case assumptions, including abandonment by Washington.

Even under this threat, there is only so much the planners can do. The alternatives they are entertaining are no substitute for the U.S. alliance. Japan’s conventional military modernisation is constrained by a waning but still significant popular anti-militarism, constitutional limitations, economic malaise and demographic decline. New security partnerships are useful but fall short of a surrogate. In the near term, Tokyo will have little choice but to continue pursuing a three-part strategy – cultivating as deep an alliance with Washington as circumstances allow, along with a more capable military and more functional security partnerships with others – even as it works through diplomatic channels to defuse tensions with adversaries to the best of its ability. But hanging over the enterprise will be doubts about U.S. reliability that Japan will feel likely increasing urgency to assuage.

Tokyo/Bangkok/Brussels, 12 December 2025