1. Japan’s Security Strategy: From “Dependence” to “Autonomy”
On 8 September 1951, the U.S.-Japan alliance was formally established through the U.S.-Japan Security Treaty, which allowed the United States to maintain military bases on Japanese soil to protect Japan from external security threats. In return, the United States assumed responsibility for Japan’s defense in the event of an attack, institutionalizing Japan’s strategic dependence on the U.S. In 1960, the two sides renegotiated a revised security treaty, renamed the Treaty of Mutual Cooperation and Security, aimed at creating a more equitable framework of military cooperation and granting Tokyo the right to consult on U.S. military activities in Japan [1]. Over time, the U.S. military presence became a structural foundation for Washington’s regional and global strategy; the alliance evolved into a mutually beneficial arrangement in which Japan enjoyed security guarantees and reduced defense burdens, while the United States maintained strategic access and forward-deployed forces in East Asia [2].
However, not all Japanese political leaders have been fully comfortable with the terms of this alliance. U.S. basing arrangements have long generated political and societal debate in Japan [3]. In pursuit of greater strategic autonomy, Japan has undergone major shifts in its security thinking and defense posture, gradually moving from the role of a defensive “shield” within the alliance toward assuming responsibilities more akin to an offensive “spear” alongside the United States in safeguarding regional and global security.
Reinterpreting the “Peace Constitution”
Amid intensifying regional security challenges, Prime Minister Abe Shinzo repeatedly advocated constitutional revision to formalize the status of the Self-Defense Forces (SDF) and expand Japan’s capacity for collective self-defense. He argued that Article 9, drafted under postwar Allied occupation, was no longer suited to contemporary strategic realities. Yet Article 96 requires that any constitutional amendment secure a two-thirds majority in both houses of the Diet and be approved through a national referendum. Despite the lack of formal amendment, on 1 July 2014, the Abe government reinterpreted Article 9 to permit Japan to exercise the right of collective self-defense, allowing support for allies under attack even when Japan itself is not directly threatened [4].
Adjusting the National Defense Program Guidelines (NDPG), Establishing the National Security Council (NSC), and Issuing the National Security Strategy (NSS)
Although the Constitution has not been amended, successive governments have used executive instruments, namely the NDPG, the NSC, and the NSS, to recalibrate Japan’s security policy and strengthen its defense capabilities.
The NDPG, a ten-year defense policy blueprint, introduced the concept of a “Dynamic Defense Force,” replacing the earlier static “Basic Defense Force” model in 2010. This concept not only underscores the mission of safeguarding territorial sovereignty but also broadens the role of the Japan Self-Defense Forces (SDF) in maintaining stability within the regional security environment. Guided by the 2010 NDPG, Japan has strengthened its force deployment across the Southwestern Islands - areas close to disputed zones with China, while enhancing its intelligence, surveillance, and reconnaissance (ISR) capabilities [5]. The NDPG also places particular emphasis on improving the SDF’s mobility to ensure credible deterrence and the ability to respond swiftly and continuously amid an increasingly complex and volatile regional security landscape.
The National Security Council (NSC) and the National Security Secretariat were established in December 2013 under the Abe Administration. According to Prime Minister Abe, the NSC would serve as a ‘control tower’ led by the Prime Minister, functioning as the central body for security policy decision-making. To support the NSC, the National Security Secretariat was established to coordinate across agencies [6]. These changes reflect a ‘top-down, whole-of-government’ approach to security governance and laid the groundwork for the reinterpretation of Article 9 of the pacifist Constitution, allowing Japan to exercise the right of collective self-defense.
In the 2013 NSS, the Abe Administration identified key sources of concern for Japan’s security, including a ‘shifting balance of power,’ ‘instability within the existing order,’ and the fact that ‘Japan’s national security model is undergoing fundamental change’ due to emerging threats in non-traditional security domains. The concept of ‘Proactive Contribution to Peace’ articulated in the 2013 NSS became the guiding principle of Japan’s defense policy, enabling the country to take a more proactive approach, particularly through alliances and international cooperation, rather than remaining confined to a purely self-defense posture as in the past [7]. The NSS thus served not only as a strategic guideline but also as a legal and political foundation for expanding defense capabilities, increasing the defense budget, and reforming Japan’s security decision-making mechanisms.
Toward a More Autonomous Defense Posture
Japan’s pursuit of greater strategic autonomy has been reflected in a series of substantive policy changes.
First, Japan has increased defense spending and undertaken comprehensive force modernization. The year 2025 marks the thirteenth consecutive year of rising defense expenditures; accordingly, Japan approved a record-high defense budget for fiscal year 2025, reaching 8.7 trillion yen (approximately USD 55.1 billion), a 9.4% increase compared to 2024 [8]. In parallel, since the late 1990s, Japan has embarked on a significant process of modernizing and upgrading its defense capabilities to strengthen its posture against external threats. Tokyo has cooperated with the United States to develop a ballistic missile defense (BMD) system, deploying sea-based missile defense through SM-3 interceptors on Aegis destroyers and land-based PAC-3 systems, and advancing plans for the Aegis Ashore system since 2017. Alongside missile defense development, Japan has also focused on modernizing its maritime and air combat capabilities. Over the past two decades, the Air Self-Defense Force (ASDF) has continuously upgraded its core fleet of F-15 fighter jets and improved radar surveillance systems. Notably, in December 2018, the Japanese government decided to convert the Izumo-class helicopter destroyer into a helicopter carrier capable of operating F-35B short takeoff and vertical landing fighters, marking a major turning point in Japan’s security strategy and paving the way for maritime power projection beyond its previously exclusive defensive orientation [9]. Overall, Japan’s defense capability development over the past two decades reflects a deliberate and incremental strategy aimed at strengthening national defense and proactively adapting to an increasingly complex regional geopolitical environment.
Second, Japan has adopted a more proactive approach in its relations with the United States. Since the end of the Cold War, the scope of the Japan–U.S. alliance has expanded from the ‘defense of Japan’ to the ‘Asia–Pacific,’ and further toward ‘global cooperation.’ Yet despite the increasingly concerning regional security environment, cooperation in areas directly tied to Japan’s immediate interests had seen limited change. In April 2015, the two sides agreed to revise the 1997 Guidelines for Japan-U.S. Defense Cooperation to adapt bilateral defense collaboration to the new security context. The 2015 Guidelines broadened the scope of cooperation to include cyber security, space defense, and ballistic missile defense (BMD). They also introduced a framework for the joint defense of Japan’s remote islands and expanded Japan’s ability to support U.S. operations beyond East Asia. However, Washington also called on Tokyo to take a more active role in burden-sharing by increasing its host-nation support for U.S. forces under the 2021 defense burden-sharing agreement [10].
The year 2024 marked a series of breakthrough developments in Japan-U.S. security relations. During Japanese Prime Minister Fumio Kishida’s state visit to the United States from 8-14 April 2024, the two sides issued a Joint Statement titled ‘Global Partners for the Future,’ highlighting several key points: (i) At the core of this ‘Global Partnership’ is enhanced defense and security cooperation, with an emphasis on modernizing the command-and-control structures of both countries in the region; (ii) The United States reaffirmed its commitment to defend Japan under Article 5 of the 1960 U.S.-Japan Security Treaty, employing its full range of capabilities including nuclear capabilities and explicitly applying this guarantee to the Senkaku/Diaoyu Islands; (iii) Japan signaled a greater contribution to the alliance by referring to efforts toward ‘strategic synchronization,’ meaning closer coordination and alignment of both countries’ defense capabilities; (iv) The Statement was accompanied by a list of more than 70 agreements showcasing the breadth of Japan–U.S. cooperation across key sectors and on a global scale [11].
Subsequently, on 28 July 2024, during the ‘2+2’ meeting between the Foreign and Defense Ministers of both countries, the two sides agreed to upgrade U.S. Forces Japan (USFJ) into a joint force headquarters under the U.S. Indo-Pacific Command (INDOPACOM). Under this restructuring, USFJ was ‘empowered’ to assume a ‘direct leadership role’ in operational planning in both peacetime and potential crisis scenarios. This development represents the most significant change to USFJ since its establishment in 1957 and constitutes one of the most substantial enhancements in Japan-U.S. military cooperation in the past 70 years [12].
Third, Japan is moving toward the position of a regional power. To assert its growing security role on the international stage, Japan established the Self-Defense Forces’ (JSDF) first permanent overseas military base in Djibouti in 2011 - the country’s only military installation abroad. In 2016, the Abe Administration announced the Free and Open Indo-Pacific (FOIP) Strategy, promoting bilateral and multilateral linkages on political, security, and economic issues across the region. Notably, in April 2023, Japan expanded its aid framework beyond Official Development Assistance (ODA) by introducing Official Security Assistance (OSA). This marked the first time Japan formally incorporated defense and security elements into its international assistance programs, enabling Tokyo to play a larger role in regional security stability [13].
Tokyo’s ambitions became even clearer when newly appointed Prime Minister Ishiba Shigeru openly voiced support for establishing an ‘Asian NATO’ to strengthen regional security cooperation [14]. These developments reflect the readiness and flexibility of Japanese policymakers amid an increasingly complex and challenging security environment. Japan’s evolution from acting merely as a ‘shield’ to becoming a ‘spear’ within the alliance with the United States not only strengthens its own security but also underscores its ambition to emerge as a regional power.
2. Assessment of Future Prospects for the Japan-U.S. Alliance
In the current context, with Japan’s new Prime Minister Ishiba Shigeru freshly inaugurated and President Donald Trump returning to the White House for a second term, the question of Japan’s level of strategic autonomy and the extent of U.S. commitment to its regional allies has become increasingly urgent. Central to this issue are the political motivations, aspirations, and implementation capacity that will shape Japan’s decisions.
With regard to external security threats, the current regional security environment compels Japan to explore new strategic models without relying solely on U.S. protection. First is the escalating tension with China over the Senkaku/Diaoyu Islands, alongside Beijing’s accelerated naval modernization and increased presence in the East China Sea, which pose potential threats to Japan’s territorial interests. Japan-China relations are inherently complex, shaped not only by territorial disputes but also by deeply rooted historical and geopolitical factors that are difficult to reconcile [15]. Second, North Korea’s nuclear weapons and ballistic missile programs have long constituted a serious security challenge for Japan. Notably, Pyongyang’s missile tests are also interpreted as messages directed at the United States, with some missiles flying approximately 3,700 kilometers - roughly the distance from North Korea to the U.S. territory of Guam [16].
Regarding political aspirations, the Ishiba Shigeru Administration has expressed a clear desire to redefine Japan’s military role within the regional order. A defense-savvy leader, Prime Minister Ishiba has, since taking office, continued to prioritize defense reforms, seeking to enhance Japan’s strategic autonomy by revising Article 9 of the Constitution, recalibrating the balance within the Japan–U.S. alliance, and diversifying Japan’s strategic partnerships while simultaneously pursuing confidence-building measures with China [17]. However, domestic public opinion remains deeply divided. According to a 2023 Kyodo News survey, 53% of respondents supported parliamentary efforts to revise Article 9, while 45% opposed the idea, reflecting persistent skepticism toward fundamentally altering Japan’s postwar identity [18].
In terms of capability, Japan currently possesses Self-Defense Forces (JSDF) regarded as among the most modern and technologically advanced militaries in Asia [19]. In the coming years, Japan aims to enhance its technological autonomy, particularly in missile systems, radar technologies, and combat management systems. However, the country’s ability to conduct fully independent operations remains constrained—especially in areas such as logistics, joint command-and-control, and long-range strike capabilities, which continue to rely heavily on U.S. support. In addition, Japan faces structural challenges, including slow economic growth, rapid population aging, and increasing fiscal pressures. Even under an optimistic scenario in which Japan musters sufficient resources to overcome these financial and political obstacles, the process of moving away from its pacifist Constitution will remain protracted, and the institutionalization of an autonomous defense strategy is likely to take at least a decade [20].
Regarding allied attitudes, Japan continues to occupy a uniquely strategic position within the US alliance system. The U.S.’s gradual move to “empower” Japan, evident in Japan’s growing autonomy in forging its own security agreements with Australia, the Philippines, and South Korea, signals a shift away from the traditional hub-and-spokes model toward a more layered network of partnerships, in which Japan has increasingly been likened to “the United Kingdom of Asia” [21]. Under President Donald Trump’s second term, the US has maintained certain strategic priorities with its Japanese ally, yet Washington has also intensified pressure on Tokyo to assume a greater share of responsibilities. The March 2025 visit of newly appointed US Secretary of Defense Pete Hegseth further underscored Japan’s irreplaceable role in America’s strategy to uphold a free and open Indo-Pacific.
3. Conclusion
The Japan-US alliance has evolved into a mutually beneficial, symbiotic partnership with an irreplaceable strategic function in the Indo-Pacific security architecture. Japan depends on the United States to safeguard its territorial security amid growing challenges posed by China, North Korea, and an increasingly volatile regional environment. Conversely, the United States relies on Japan to sustain its military presence, coordinate its alliance network, and constrain China’s expanding influence. Despite differences in capabilities and status, both countries recognize the indispensable role of the other in maintaining regional order. Rather than drifting apart or weakening, the alliance is being strengthened through a more balanced distribution of responsibilities. Japan is gradually assuming a more proactive role in regional security affairs, while the United States continues to provide strategic support, advanced technologies, and global deterrence capabilities.
Despite significant internal constraints, Japan continues to pursue the goal of strategic autonomy. Article 9 of its Constitution, together with a public wary of any return to militarism, has compelled Tokyo to adopt a gradual and cautious approach to defense reform. Nevertheless, over the past two decades, Japan has demonstrated a clear determination to recalibrate its strategic thinking and implement more substantive policy measures. In the context of President Donald Trump’s return to the White House, accompanied by a more isolationist foreign policy outlook, Japan has gained additional incentive to accelerate its quest for autonomy, seeking to mitigate strategic risks should US security commitments weaken.
Japan’s current strategy reflects a dual-track effort: strengthening its alliance with the United States while gradually expanding the scope for independent action. In recent years, Tokyo has taken an increasingly active role in multilateral and minilateral security mechanisms. It has advanced its defense diplomacy by deepening cooperation with partners both within and beyond the region. These initiatives indicate that Japan is steadily assuming a coordinating role within the broader US-led alliance network. In some cases, such cooperation has proceeded without the need for direct US involvement, underscoring Tokyo’s shift from a reactive posture to a more proactive strategic profile.
In strengthening its autonomous defense capabilities and expanding its strategic latitude, Japan’s approach, maintaining its core alliance with the United States while proactively advancing cooperation with partners both within and beyond the region, illustrates a flexible and effective model. This experience offers relevant lessons for other states seeking to design appropriate cooperation mechanisms, reinforce self-defense capacities, and safeguard national interests amid an increasingly competitive and volatile regional security environment.
Le Ngoc Mai, Nguyen Hop Chau
This Article was first published as “Japan in the US Alliance Vise: Autonomy or Dependence?” on World Affairs Journal (ISSN: 2815-6447), Issue 4, pp.47-52
*Transalated by HCDH
REFERENCES:
[1]. Japan-U.S. Security Treaty [1960] https://www.mofa.go.jp/region/n-america/us/q&a/ref/1.html
[2]. H. D. P. Envall [2023], Japan's American Alliance: Forgoing Autonomy for Deterrence, https://hd-penvall.com/chapters/japans-american-alliance-forgoing-autonomy-for-deterrence/
[6]. Adam P. Liff, Japan's Security Policy in the "Abe Era": Radical Transformation or Evolutionary Shift?, May 2018, https://insr.org/2018/05/japans-security-policy-in-the-abe-era-radical-transformation-
[7]. National Security Strategy, December 17, 2013, https://www.cas.go.jp/jp/siryou/131217anzen-hoshou/nss-e.pdf
[9]. Yoshihiro Inaba, Japan Starts Conversion Work on Second Izumo-class DDH, April 18, 2022, https://www.navalnews.com/naval-news/2022/04/japan-starts-conversion-work-on-second-izumo-
[10]. Nikkei, Japan and US agree on 1-year cost-sharing deal for hosting troops, February 17, 2021, https://asia.nikkei.com/Politics/International-relations/Japan-and-US-agree-on-1-year-cost-sharing-deal-for-hosting-troops
[11]. United States–Japan Joint Leaders Statement, April 10, 2024, https://www.whitehouse.gov/briefing-room/statements-releases/2024/04/10/united-states-japan-joint-leaders-statement
[14]. Hiroyuki Akita, China wants ability to invade Taiwan by 2027, U.S. admiral says, April 24, 2024, https://asia.nikkei.com/Editor-s-Picks/Interview/China-wants-ability-to-invade-Taiwan-by-2027-U.S.-admiral-says
[18]. Kyodo News, Japan split over parliament debate on Constitution revision: poll, May 02, 2023, https://english.kyodonews.net/news/2023/05/b3108393fb5e-japan-split-over-parliament-debate-on-constitution-revision-poll.html
