Pragmatism should continue to guide Lee's second year of diplomacy with Japan

Cho Yang-hyun

The author is a professor at the Korea National Diplomatic Academy and head of the Japan Relations Division of Reset Korea.

The first year of the Lee Jae Myung administration's diplomacy toward Japan can largely be considered a success. Despite concerns in Japan that the inauguration of a progressive South Korean government might revive disputes over historical issues, the new administration made clear from the outset that it would pursue pragmatic diplomacy centered on national interests while maintaining cooperation with Tokyo. As a result, a series of summit meetings held on the sidelines of the Group of 7 summit and later in Tokyo, Busan, Nara and Andong helped institutionalize regular shuttle diplomacy.

Equally significant, the bilateral agenda has expanded beyond historical disputes to include economic security, supply chains and advanced technologies. The prolonged Russian invasion of Ukraine and instability in the Middle East underscored the shared challenge of securing energy supplies and resilient supply chains. South Korea and Japan have since broadened cooperation on liquefied natural gas procurement, critical minerals and supply chain resilience while exploring partnerships in AI, semiconductors, space and biotechnology.

The Lee administration has also taken a pragmatic approach to historical issues. Rather than placing past disputes at the center of bilateral relations, it has sought humanitarian cooperation, including efforts to recover the remains of Korean victims at the Josei coal mine. This approach acknowledges domestic public opinion while preventing historical issues from overwhelming the broader relationship.

Nevertheless, major challenges remain, the most significant of which is the difference between the two governments' strategic outlook. The Sanae Takaichi administration has prioritized strengthening military deterrence against North Korea and deepening South Korea-Japan and trilateral South Korea-U.S.-Japan security cooperation in response to China. The Lee administration, while supporting trilateral cooperation, seeks to avoid creating the impression that such cooperation is aimed at containing China. Instead, it has promoted the restoration of trilateral cooperation among South Korea, China and Japan as part of a broader strategy emphasizing dialogue and peaceful coexistence on the Korean Peninsula.

These differing strategic perspectives, together with unresolved historical issues, continue to constrain bilateral cooperation. They also explain why security initiatives often generate greater political sensitivity than economic cooperation despite growing agreement on the need for closer coordination in an increasingly uncertain regional environment.

The recent debate over a possible Acquisition and Cross-Servicing Agreement (ACSA) illustrates these constraints. Japan has already concluded such agreements with 11 countries, including the United States, Britain, Australia, France, Canada, India and the Philippines, and views a similar arrangement with South Korea as a natural next step. Given the growing alignment among North Korea, China and Russia, Washington and Tokyo are likely to continue encouraging an ACSA to improve security cooperation in East Asia, and Seoul will find it increasingly difficult to dismiss the proposal outright.

But the agreement carries far greater political symbolism in South Korea than it does in Japan because it is widely viewed as expanding cooperation with the Japan Self-Defense Forces. Many supporters of the Democratic Party and civic groups continue to see the issue through the lens of historical grievances, and the government cannot ignore those domestic concerns. Rather than pursuing a comprehensive agreement immediately, a phased approach would be more realistic, beginning with cooperation in disaster relief, humanitarian assistance and peacekeeping operations before considering broader institutionalization.

Another variable is domestic politics. An upcoming Cabinet reshuffle and the Democratic Party leadership election could influence both the direction and pace of policy toward Japan. If more nationalist or progressive voices gain influence within the ruling party, the administration's room for diplomatic maneuver could narrow. As a result, stable relations with Japan should be managed as a matter of long-term national strategy rather than the ideological preference of any particular government.

The central task of South Korea-Japan diplomacy is no longer simply managing historical disputes but translating shared future interests into practical cooperation. As the international environment grows more uncertain, the two countries will share more strategic interests, strengthening public support for pragmatic diplomacy focused on national interests. Whether the two governments can achieve a long-delayed state visit by a South Korean leader to Japan, adopt a new bilateral joint declaration, advance South Korea's accession to the Comprehensive and Progressive Agreement for Trans-Pacific Partnership, deepen cooperation in supply chains and advanced industries and gradually expand security cooperation, including an ACSA, will shape the future of bilateral relations.