The Koreas | Diplomacy | East Asia

Japan-Korea: Working Together as Like-Minded Countries?

Japan and South Korea share more than enough to work together on North Korea — but less than is often assumed.

Japanese Prime Minister Takaichi Sanae and South Korean President Lee Jae-myung attend a summit meeting in Andong, South Korea, May 19, 2026.

It is frequently argued that “Japan and South Korea are like-minded countries who share values and ought to strengthen their cooperation in dealing with North Korea.” The question worth asking is what the two countries are actually “like-minded” about — and what they are not.

There is no settled definition in international politics of “like-minded countries” — a concept increasingly prominent in Japanese diplomatic discourse as dōshikoku —, but the term generally refers to countries that share objectives or an understanding on specific issues. The two countries are not automatically like-minded simply because they are both democracies, nor do their policies automatically align across diverse fields because they are both U.S. allies. The degree of alignment has to be assessed issue by issue.

Japan-South Korea relations on the North Korean issue do have an evident duality. On the “threat” dimension, the two are quite robustly like-minded: both are concerned about North Korea’s growing nuclear and missile capabilities, and there is considerable room for cooperation in countering cyberattacks and cryptocurrency theft. The importance of Japan-South Korea security cooperation is also growing as the Russia-North Korea military relationship deepens. In managing relations with an unpredictable U.S. president, too, the bilateral Japan-South Korea framework has become if anything more important than the broader trilateral one.

The differences become apparent, however, the moment North Korea is treated not as a “threat” but as a potential “negotiation partner.” In South Korean eyes, North Korea is simultaneously a military threat and one half of a divided nation sharing a common language. Depending on the administration, the emphasis varies, but Seoul can never entirely set aside the questions of peaceful coexistence and eventual reunification.

Japan, by contrast, regards North Korea as a foreign country across the sea. Drones do not fly over from North Korea to Japan as they do to South Korea, and Japan’s North Korea policy is heavily constrained by the abduction issue — a factor absent for every other country in the region. Even if progress were made on nuclear and missile issues, it would be politically impossible for Tokyo to move toward normalization without meaningful progress on abductions.

Even if both Tokyo and Seoul were to support “dialogue” and “diplomacy” with Pyongyang, the underlying expectations would differ. Seoul values dialogue that eases inter-Korean........

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