ROK, U.S., and Japan Officials Discuss Conducting Trilateral Military Training

This is something that has been done in the past, but was suspended under the liberal Moon Jae-in administration. Now with a new President it appears restarting trilateral cooperation may soon become a reality:

The defense chiefs of South Korea, the United States and Japan agreed Saturday to step up cooperation to counter North Korea’s missile threats through their combined regular security exercises, including missile warning drills, Seoul’s defense ministry said. 

Lee Jong-sup and his U.S. and Japanese counterparts, Lloyd Austin and Nobuo Kishi, reached the agreement during their gathering held on the margins of the annual Shangri-La Dialogue in Singapore.

Korea Times

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