U.S. security guarantees in East Asia are becoming uncertain and transactional, pushing South Korea and Japan to reduce reliance on Washington.

Japan and South Korea should form a strong bilateral defense alliance, including joint exercises, intelligence sharing, and defense industry cooperation to counter threats from North Korea and China.

Overcoming historical tensions is essential for both countries to achieve greater strategic autonomy and regional stability.

The geopolitical landscape in East Asia is undergoing a structural change due in large part to uncertain U.S. security guarantees. That extended deterrence has for decades served as the backbone of stability in the region is a given. That Washington’s foreign policy is increasingly transactional in nature, however, is driving its front-line allies to reassess the value of the guarantees that it extends. In order to preserve their own security and democracy in the face of a declining U.S. commitment, South Korea and Japan must establish a robust defence alliance and create a range of joint industrial initiatives that would allow them to develop their own defence technologies independent of external suppliers. Indeed, the two countries could even pursue broader security integration, ensuring that their relationship remains the anchor of stability in the region in the face of threats from the North as well as China. A formal alliance between the two countries would enable them to mitigate the kinds of external volatility that are beyond their control while at the same time protecting in common their shared democratic values and interests, all without needing to rely on the West.

However, when the United States’ posture has become unpredictable since the Trump administration began, its commitment to protect and maintain security together with other countries in crisis has become a subject of many concerns. The United States is maintaining a large number of its military personnel and bases in many parts of the world. It is natural to expect that it will fulfil its commitment and maintain security together with other countries. However, since the beginning of the Trump........

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