President Donald Trump’s decision to shorten Ulchi Freedom Shield (UFS) shows that disputes far removed from the Korean Peninsula can spill into core U.S.-South Korea security arrangements, creating new uncertainty for Seoul as it pursues wartime operational control (OPCON) transfer, nuclear-powered submarines and renewed diplomacy with North Korea.

The annual exercise was scheduled to run from Aug. 17 through Aug. 27 before Trump directed Defense Secretary Pete Hegseth to “substantially reduce” the military exercise with South Korea. Trump linked the decision to President Lee Jae Myung’s alleged refusal to help the U.S. “denuclearize” Iran and his own relationship with North