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Over the two years since the announcement of its current national security and defense strategies, Japan has taken major steps toward increased defense capabilities and closer cooperation with the United States as well as other allies and partners. The Biden-Kishida summit of last April further extended alliance commitments in such areas as joint operations, regional defense networks, science and technology collaboration, information and cybersecurity measures, and defense industrial collaboration.
The recent launch of a new channel for armaments-related dialogue could for the first time broaden bilateral engagement across a full spectrum of acquisition interests. Common requirements for capabilities like uncrewed aircraft and hypersonic interceptors offer new opportunities for cooperative acquisition, while strengthened supply chain arrangements can lead to closer collaboration among the industrial bases of the United States, Japan, and other allies. However, achieving this potential will require not only resets in policy on both sides but an evolution to approaches more characteristic of true partnerships than traditional supplier-customer relations.
Cold War–era policies and agreements set a static pattern for engagement in U.S.-Japan defense programs. Transfers of U.S. equipment and small-scale research projects occurred through narrow channels defined by restrictions on U.S. technology release and a general ban on Japanese defense exports.
Despite recurring problems with ineffective management and terms for industry workshare, there was little incentive to change ingrained patterns of interaction. Policy and institutional constraints on both sides, a lack of sustained attention to defense requirements, and growing friction over U.S. technology release to Japan undercut opportunities for cooperative acquisition programs—as evident in inconclusive dialogue on support for Japan’s next-generation F-X fighter, the outcome of which led Japan to join the United Kingdom and Italy in the Global Combat Aircraft Program (GCAP).
Describing armaments cooperation as an alliance builder may only state the obvious, but for many years acquisition and industrial cooperation remained at the periphery of the U.S.-Japan dialogue under the Security Consultative Committee (also known as 2+2) framework. In the absence of perceived operational urgency, efforts to define operational roles and responsibilities for U.S. and Japanese forces never bridged critical gaps from capabilities to requirements, and then to acquisitions.
Recent challenges to global and regional security concerns have encouraged both the United States and Japan to reconsider their approach to alliance operations. Increased emphasis on joint operations now extends to closer alignment with other allies. As seen in the Research, Development, Test and Evaluation Projects as well as the Security of Supply Arrangement signed in January 2023, greater sharing of industrial and technological resources has been recognized as a critical enabler to meeting joint capability needs.
These developments prepared the way for defense initiatives announced at the U.S.-Japan summit on April 10. Among these measures was a new framework for dialogue on cooperative acquisition interests: the Defense Industrial Cooperation, Acquisition, and Sustainment (DICAS) forum. DICAS has replaced an outdated Systems and Technology Forum whose activities were largely confined to oversight of research projects.
Under the Terms of Reference Arrangement signed last June by senior defense acquisition officials, initial DICAS activities have concentrated on working groups to address procurement and support matters that impact regional security operations—ship repair; aircraft repair; supply chain support; and coproduction of advanced missiles. Working group dialogue in all of these areas, followed by production and support arrangements, should continue well into 2025. An agenda for the expansion of DICAS activities into broader areas of acquisition interests will be determined through talks by incoming Trump administration officials with their Japanese counterparts.
Alongside DICAS there have been notable initiatives in expanding the scope of bilateral—and multilateral—engagement on defense acquisition programs:
Glide Phase Interceptor (GPI): An agreement signed last May to jointly develop a glide phase hypersonic missile defense system draws on precedents from the joint development of the Standard Missile 3 Block IIA ballistic missile interceptor. However, terms of the GPI Cooperative Development program have evolved to feature more balanced workshare arrangements and closer engagement between industry participants on each side.
Collaborative Combat Aircraft (CCA): The U.S. Air Force plans for acquiring uncrewed “loyal wingman” aircraft include a substantial role in international collaboration. Following inconclusive dialogue on the F-X fighter, U.S. and Japanese defense officials turned to uncrewed air systems as a promising path for joint programs. In October 2023 the United States and Australia announced plans to explore work with Japan on developing uncrewed aircraft. The following December, the United States and Japan concluded a project agreement for research on CCA-related AI technology—the first under their new RDT&E arrangement. Japan’s participation in a recent U.S. Air Force–hosted International CCA Symposium is a promising development for its engagement in multinational CCA programs.
Advanced Trainer and Tactical Aircraft: Both countries need to replace outdated training aircraft. Of possible alternatives, one path to meeting common requirements could lie in Japan’s use of the new U.S. T-7A trainer, followed by joint development of a tactical training aircraft derived from that airframe. Bilateral dialogue on pilot training requirements began last July and will continue into 2025. Success in determining common requirements could enable both sides to align their acquisition schedules to support a joint program.
From Bilateral to Multilateral Engagement: U.S.-Japan interaction on defense acquisition can no longer stand apart from a general trend toward multilateral programs. The AUKUS partnership on clear submarines and other leading-edge defense capabilities underlines this reality. So does Japan’s decision to join the GCAP with the United Kingdom and Italy. GCAP terms for government oversight and industry joint venture work are setting critical precedents for future Japanese collaboration with the United States and other international partners. Through GCAP, Japanese government policies and industry attitudes toward international engagement have evolved in a manner hardly expected just a few years ago.
Evolving Armaments Cooperation to Meet Alliance Needs: Developing armaments cooperation to support a more dynamic U.S.-Japan operational partnership will require substantial policy, institutional, and cultural adjustments on both sides.
The United States and Japan must bridge the institutional gaps that separate policy, requirements, and acquisition in defense dialogue. Integrating policy-led bilateral government dialogue on roles, missions, and capabilities with DICAS activities would enable work with the military services to align requirements, identify cooperative acquisition opportunities, and apply the results of joint technology research to tangible effect.
Both countries will have to depart from a security assistance-focused approach to cooperation. While oversight through government-managed foreign military sales processes will remain necessary to transfer some critical technologies, the United States cannot expect Japan and other key allies to act as resource-sharing partners while still being treated as customers on export control and technology release.
For its part, Japan cannot treat access to leading-edge U.S. defense systems and technologies as alliance entitlements. A traditionally reactive approach to dialogue on defense programs costs Japan opportunities to influence the United States and other partners. Limited communication channels and weak overseas representation continue to obstruct Japan’s engagement at all levels of interaction on defense requirements and acquisitions.
As Japan and other allies insist on sovereign control over technologies embedded in the defense systems they acquire—and viable alternatives to U.S. sourcing increase—a more responsive U.S. approach to information disclosure and systems release is a matter of increasing urgency. Its actions on export control and technology release will in turn depend on continued Japanese government efforts to implement more flexible export control measures and strengthen information security procedures.
Institutions and Culture: Policy statements notwithstanding, the real degree of U.S. commitment to cooperative acquisition will depend on effective implementation through dedicated staffing. Proposals to strengthen Department of Defense support for international programs as embodied in the FY 2025 National Defense Authorization Act (NDAA) would clearly signal U.S. intent to work more closely with key allies and partners.
Ingrained patterns of behavior may pose the greatest challenge facing U.S.-Japan cooperation on future defense acquisitions. Some U.S. officials still view transfers of defense capabilities to Japan as security assistance tasks, while industry counterparts treat a dominant position in Japan’s defense market as an entitlement. Interest in accessing Japan-produced defense hardware and maintenance facilities for support of deployed U.S. forces will inevitably contend with pressure to protect domestic U.S. production bases.
Meanwhile, some defense community stakeholders in Japan still resist the reality that licensed production and subsidized indigenous programs can no longer sustain their industrial and technology base. Closer international engagement should encourage defense planners in Japan to focus on aligning equipment programs with international standards rather than catering to “unique” requirements that lead to non-interoperable capabilities.
Incremental amendments to export control measures are unlikely to provide enough incentive for Japan’s defense industry (let alone nontraditional suppliers) to engage international partners. Export promotion measures in the Japanese government’s new defense industry policy are a positive step in this direction, as now evident in Japan’s campaign for Australia’s future frigate program.
Government-Industry Engagement: Successful international defense acquisition programs rely on government-industry teams to plan strategies, seek opportunities, negotiate agreements, ensure follow-on support, and promote reciprocal investments in industrial base resources—all features largely absent in U.S.-Japan interaction to date. While government dialogue on defense acquisition has included exchanges with defense industry associations, the level of such interaction has often been perfunctory in content, with little impact on government measures in either country.
Planning for DICAS indicates a substantially greater role for involvement with industry that could extend to generic policy concerns as well as discussion of specific requirements with appropriate industry groupings—all new territory for government-industry engagement on U.S.-Japan defense programs.
Contrary to challenges facing the incoming Trump administration elsewhere, prospects for further strengthening the U.S.-Japan alliance remain positive. Recent tension over a Japanese industry’s attempt to acquire a U.S. steelmaker should not distract attention from the strategic benefits of closer cooperation in the acquisition of defense capabilities.
To realize such benefits U.S.-Japan interaction must mature from management through stovepiped channels toward full integration into an alliance framework that provides operational and material benefits to both sides. Some challenges facing this goal will require years of institutional evolution to address, but work on others can proceed now:
Based on these institutional developments, the new administration should develop the DICAS channel to:
Gregg Rubinstein is an adjunct fellow with the Japan Chair at the Center for Strategic and International Studies in Washington, D.C.
