A 2019 analysis of the US-Japan alliance by Elena Atanassova-Cornelis and Yoichiro Sato argued that Japan's hedging strategy against possible US abandonment enhances the bilateral alliance in the short term while paving the way for Japan's pursuit of strategic autonomy in the medium to long term, and raised linked strategic-uncertainty questions: whether hedging-driven alignment diversification ends in genuine autonomy or a re-strengthened burden-sharing equilibrium, and whether minilateral configurations (trilaterals, the Quad) remain supplementary to, or progressively supplant, the hub-and-spoke alliance system for traditional-security missions. Two further strands of the same trajectory question remain open: the likelihood and form of a US accommodation with China and the stability consequences of firm US commitment versus managed withdrawal, and the long-term effects of legal and doctrinal ambiguity around collective self-defence on constitutional reinterpretation and operational thresholds. These strands are actively debated in 2026.

Background

The United States and Japan have been formally allied since the 1951 US-Japan Security Treaty, revised in 1960 as the Treaty of Mutual Cooperation and Security. Rather than a NATO-style multilateral pact, post-war US security policy in Asia rested on a 'hub-and-spoke' system: separate bilateral alliances running from Washington (the hub) to Tokyo, Seoul, Canberra, Manila and Bangkok (the spokes), with few obligations among the spokes themselves. A basic theorem of alliance theory, the alliance security dilemma, holds that every ally simultaneously fears abandonment (the partner decouples or defects in a crisis) and entrapment (being dragged into the partner's wars); in an asymmetric alliance the junior ally typically fears abandonment more. Hedging denotes a state's attempt to insure against these opposite risks by mixing instruments - strengthening the primary alliance while also diversifying security partnerships and building national capability - rather than committing fully to one course. Strategic autonomy refers to the capacity to act in one's own security without depending on another state's decision to fight. In a 2019 article in The International Spectator, Elena Atanassova-Cornelis and Yoichiro Sato analysed how the global transition from unipolarity toward multipolarity and China's challenge to US security dominance re-polarised this dilemma: entrapment concerns rose for Washington, abandonment anxieties for Tokyo. They argued that the United States increasingly demands 'mutuality' in burden-sharing (greater allied defence spending and roles) while keeping its defence commitments deliberately ambiguous, and that this ambiguity, combined with relative US decline, incentivises Japan to step up 'preparations for abandonment'. Their central claim was that Tokyo's hedging enhances the bilateral alliance in the short term but paves the way for Japan's pursuit of strategic autonomy in the medium to long term. Minilateralisation denotes the growth of informal small-group security alignments - the US-Japan-Australia trilateral strategic dialogue, the Quadrilateral Security Dialogue (Quad: US, Japan, Australia, India), later AUKUS (Australia-UK-US) and the US-Japan-Australia-Philippines 'Squad' patrols - layered onto the bilateral treaties, sometimes described as a 'power web' of interlocking partnerships. A second enabler is legal: Japan's constitution (Article 9) renounces war, and the 2014 Cabinet reinterpretation, operationalised in the 2015 security legislation, permits 'collective self-defence' only under three conditions - an armed attack on a close foreign country that threatens Japan's survival, absence of other appropriate means, and use of force limited to the minimum necessary - leaving substantial doctrinal ambiguity about operational thresholds for employing the Self-Defense Forces (SDF). Subsequent developments - Japan's 2022 National Security Strategy with counterstrike capabilities and a pledge to roughly double defence spending to 2 percent of GDP by 2027, reciprocal access agreements with Australia and the UK, and the joint Japan-UK-Italy fighter programme - have sharpened exactly the trajectory question the 2019 article posed.

Problem Statement

The research problem, stated as one coherent problem with linked components - the autonomy, burden-sharing-equilibrium and minilateralisation strands and the US-accommodation and legal-doctrinal strands: determine the trajectory of the US-Japan alliance under Japanese hedging and US commitment uncertainty - specifically, (i) under what conditions and through what mechanisms Japan's hedging-driven alignment diversification and capability build-up evolve into genuine strategic autonomy, as against consolidating a re-strengthened bilateral burden-sharing equilibrium; (ii) whether the minilateral alignments layered onto the bilateral treaties reinforce and supplement the US-led hub-and-spoke alliances in the short term while progressively supplanting them in the medium to long term in traditional (war-fighting) security - the alignments examined so far include the US-Japan-Australia trilateral strategic dialogue and, as the wider configuration, the Quad, with AUKUS and the US-Japan-Australia-Philippines 'Squad' as later instances - and under what conditions such a transition would occur; (iii) how likely a US accommodation with China is, in what form, with what role for Japan, and what the consequences for regional stability would be if Washington instead chose firm commitment or managed withdrawal; and (iv) what the long-term effects of legal and doctrinal ambiguity, notably the three conditions attached to collective self-defence since 2014, are on further constitutional reinterpretation, on operational thresholds for employing the Self-Defense Forces, and on interoperability with minilateral partners. The four components (i)-(iv) are linked, and determining the trajectory turns on the conditions, mechanisms and observable implications distinguishing the competing trajectories (autonomy versus renewed equilibrium; supplement versus supplant; accommodation versus commitment or withdrawal) and on the long-term effects of legal and doctrinal ambiguity, assessed against the documented record of Japanese and US alliance behaviour.

References

  1. Elena Atanassova-Cornelis and Yoichiro Sato, 'The US-Japan Alliance Dilemma in the Asia-Pacific: Changing Rationales and Scope', The International Spectator 54(4):78-93, 2019. DOI: 10.1080/03932729.2019.1665272. https://doi.org/10.1080/03932729.2019.1665272
  2. Elena Atanassova-Cornelis, 'Alignment Cooperation and Regional Security Architecture in the Indo-Pacific', The International Spectator 55(1):18-33, 2020. DOI: 10.1080/03932729.2020.1712132. https://doi.org/10.1080/03932729.2020.1712132
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