Policy Briefs on Peace and Security in Northeast Asia

This report examines the relative decline of American power and status in East Asia, through a South Korean perspective. An ‘East Asia without the United States’ was once unthinkable because the American economic and military presence in the region was so dominant and beneficial to many of its countries. Hence, intellectuals in East Asian countries have begun to broaden their views on the matter and craft new narratives about America’s role in the area. This work addresses the convoluted dynamics that arise from this changing role of the world’s foremost superpower.

This report addresses the denuclearization of North Korea which remains an indispensable objective not only for Japan but for the entire international community. Complete denuclearization has become a long-term goal rather than an immediately achievable outcome. The international community must simultaneously prevent North Korea from further expanding its nuclear arsenal and ensure that these weapons are never used. This dual approach—pursuing denuclearization while managing immediate nuclear risks—requires careful coordination among Japan, the Republic of Korea (ROK), and the United States.

This policy brief reviews the lessons of academic scholarship on deterrence and assurance in order to unpack how and why tools of assurance work. In pursuit of stable deterrence on the Korean Peninsula, all parties ought to be reassuring one another. While there are trade-offs between communicating deterrence and reassuring adversaries, both are necessary for a stable relationship and reducing the probability of crisis or war. First, I offer definitions for key terms. Second, I review scholarly findings on credible communication and signalling. Third, I apply theory to the policy problem of stabilizing the Korean Peninsula.

This report synthesizes the findings of the 2025 Toda Research Cluster on Reassurance on the Korean Peninsula, bringing together theoretical, national, and policy perspectives from the United States, South Korea, Japan, China, and Russia. In the context of rising great-power rivalry and the consolidation of competing blocs, the contributors argue that deterrence alone cannot sustain stability. Drawing on insights from the five core papers, the report identifies mutual reassurance as an essential complement to deterrence. The analysis highlights converging recommendations for arms control-based risk reduction, revitalized inter-Korean and multilateral channels, calibrated adjustments to alliance posture, and leadership-level credibility. While acknowledging the long-term goal of denuclearization, the report emphasizes pragmatic pathways for near-term stabilization, offering a structured framework for building a durable reassurance architecture in Northeast Asia.

This policy brief examines the diplomatic challenges facing the Takaichi Administration. A clear direction in foreign and security policy can be inferred from the new prime minister’s cabinet appointments. This paper will delve into the structural challenge of the Takaichi administration's political vulnerability and explore the expectations and concerns of key international actors (the US and China) regarding this fragility. Finally, it will offer specific policy recommendations on how the Takaichi administration should execute a robust foreign and security policy to protect Japan's national interests under unstable political conditions, focusing particularly on diplomacy with South Korea to avoid undermining the critically important Japan–US–South Korea security cooperation.