The Path of U.S.-South Korea-Japan Cooperation: Strengthening Trilateral Relations Amid Uncertainty

Key Chapter Title List

1. U.S.-ROK-Japan Trilateral Cooperation: Past, Present, and Future
2. How to Consolidate U.S.-ROK-Japan Cooperation Under New Leadership Changes
3. Beyond Historical Memory: South Korea's Internal Divisions and U.S.-ROK-Japan Trilateral Cooperation
4. Beyond Security: Human Rights as a Foundation for Japan-ROK Cooperation
5. Navigating Uncertainty: Risk Management in U.S.-ROK-Japan Trilateral Cooperation
6. U.S.-ROK-Japan Economic Security Cooperation: Clarifying Resilience, Competitiveness, and Protection
7. Strengthening U.S.-ROK-Japan Cooperation in Maritime and Economic Security
8. Defending the Energy Security Path: U.S.-ROK-Japan Strategic Cooperation
9. U.S.-ROK-Japan Trilateral Cooperation in Countering North Korean Cyber Threats
10. How Will a Second Trump Term Shape U.S.-ROK-Japan Trilateral Cooperation on North Korea?
11. U.S.-ROK-Japan Trilateral Exercises as a Means of Strategic Communication
12. Command and Control in U.S.-ROK-Japan Relations: Cooperation and Sovereignty
13. Conventional-Nuclear Force Coordination: A Path Forward for U.S.-ROK-Japan Trilateral Security Cooperation
14. U.S.-ROK-Japan Trilateral Cooperation on Non-Combatant Evacuation Operations

Document Introduction

This report is compiled from the featured roundtable in the January 2025 issue of *Asia Policy*, bringing together in-depth analysis from fifteen leading scholars from South Korea, Japan, and the United States. The core research context is the commencement of Donald Trump's second term in January 2025, the inauguration of Japan's Shigeru Ishiba cabinet, and the domestic political uncertainty triggered by the impeachment of South Korean President Yoon Suk-yeol. The report aims to systematically assess the sustainability of U.S.-ROK-Japan trilateral cooperation in the face of leadership transitions, historical legacies, domestic political polarization, and increasingly severe regional security challenges, and to provide multidimensional policy recommendations for deepening and institutionalizing cooperation.

The report first traces the origins and evolution of trilateral cooperation from a historical perspective, noting that it began in the 1990s to address the North Korean nuclear issue but has long been affected by fluctuations in Japan-ROK relations, shifts in U.S. policy, and misalignment of strategic interests among the countries. The 2023 Camp David Summit marked a historical high point for cooperation, achieving substantive progress in areas such as military exercises, real-time missile warning data sharing, supply chain early warning systems, and economic security dialogue. However, these achievements are highly dependent on the personal political will and strategic consensus of the three leaders—Yoon Suk-yeol, Joe Biden, and Fumio Kishida—and its institutional foundation remains fragile.

Multiple scholars delve into the core structural obstacles hindering the deepening of trilateral cooperation. Political polarization within South Korea is seen as a key challenge, particularly regarding historical issues and Japan policy, where significant divisions exist between conservative and progressive voters and elites. This could lead to drastic swings in foreign policy with changes in government. Although Japan-ROK relations have recently warmed due to shared strategic interests, historical perception issues such as "comfort women" and forced labor are far from resolved, as evidenced by the 2024 disagreement over the Sado Mine memorial activities. Public surveys show that while a majority of the public in both countries supports bilateral and trilateral security cooperation, South Koreans are primarily concerned about the North Korean threat, while the Japanese public is more focused on countering China, reflecting differences in cooperative motivations.

The report features an analysis of the opportunities and risks for trilateral cooperation across various specific domains against the backdrop of a potential return of Trump's "America First" policies. In the realm of economic security, the mix of objectives for policy tools (such as investment screening, industrial subsidies) differs among the three countries, with the U.S. leaning more towards protectionism while Japan and South Korea are relatively cautious. Future cooperation needs to strike a balance between enhancing supply chain resilience, boosting industrial competitiveness, and implementing protective measures. In the security domain, the report explores specific pathways such as countering North Korean cyber threats, conducting trilateral military exercises as a means of strategic communication, improving command and control coordination, and developing the concept of "conventional-nuclear force coordination." Energy security cooperation (e.g., LNG, civil nuclear energy, clean hydrogen) and maritime transport security are also seen as promising directions for cooperation to reduce dependence on China and Russia.

Finally, the report emphasizes the urgency of institutionalization. The establishment of the Trilateral Coordination Secretariat in November 2024 is an important step, but higher-level coordination channels such as regular summit meetings need further institutionalization. Scholars recommend strengthening inter-parliamentary exchanges among the three countries, leveraging the bridging role of experts and opinion leaders, and expanding Japan-ROK societal consensus within frameworks of universal values such as human rights. This would transcend historical disputes and lay a more solid social and value foundation for trilateral cooperation. Overall, this roundtable concludes that despite an uncertain path ahead, maintaining and deepening U.S.-ROK-Japan trilateral cooperation aligns with the fundamental strategic interests of the three countries in the face of continued North Korean provocations, deepening China-Russia-North Korea coordination, and challenges to the Indo-Pacific regional order.