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Home / Asia / Bridging the divide: the significance of the US-South Korea-Japan trilateral
Asia, Alliances

August 17, 2023

Bridging the divide: the significance of the US-South Korea-Japan trilateral

By Daniel DePetris

The Philippines may be the oldest US treaty ally in Asia, but South Korea and Japan are arguably the closest. The US-South Korea mutual defence treaty will turn 70 years old this October, and both countries have spent the last several months implementing the April 2023 Washington Declaration that reiterates Washington’s extended deterrence commitment to Seoul in the face of North Korea’s growing nuclear and missile capability. Japan, meanwhile, is undergoing its own defence transformation of sorts, planning a doubling of its defence budget over the next five years and boosting the interoperability of their forces with countries from the Philippines to Australia.

The bilateral relationship between South Korea and Japan, however, has always been a one-step forward, two-steps back situation. Imperial Japan’s thirty five-year colonisation of the Korean Peninsula before and during the Second World War, and all of the human rights abuses that went along with it, was the albatross around the relationship’s neck. Japan and South Korea were more than happy to work with the United States, but the United States was considered lucky if it could drag Japan and South Korea into the same room.

South Korea-Japan relations still aren’t rosy, but they are far better off today than they were four or five years ago.

Read at Lowy Institute

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