South Korea’s Impeachment Crisis Strains Its Alliance with the U.S

President Yoon Suk Yeol has changed the course of South Korea’s diplomacy like no leader before him. He put his country in lock step with the United States by countering North Korea with sanctions and joint military drills. He won Washington’s plaudits when he overcame a century of historical grievances Koreans held against Japan​ and helped lay the ground for trilateral cooperation to deter China.

He sang the praises of Western values such as freedom. He credited the alliance with ​Washington for making South Korea’s ​ascent as a global economic and cultural powerhouse possible. He moved South Korea ​more assertively onto the global stage, criticizing Russia’s invasion of Ukraine as “a violation of international law” and selling weapons​ and ammunition to countries that supported Ukraine. And he stood up against China, ​which South Korea ​had long feared as a bully but needs as a trading partner, by opposing its “unlawful maritime claims” in the Indo-Pacific region.

Now​, as he is locked out of power following his impeachment, his foreign policy — and ​Washington’s painstaking alliance-building in Northeast Asia —​ faces the prospect of unraveling. Mr. Yoon was not impeached for his foreign policy. But his diplomatic agenda​ — his greatest legacy​ — could be one of the biggest casualties of his downfall.

“Washington couldn’t have asked for a better ally and partner than the Yoon government,” said Duyeon Kim, a fellow with the Center for a New American Security. “Until we know who South Korea’s president is, the U.S. just lost a key partner at the leader level whose personal conviction aligns with Washington’s values and approach to regional and global issues, particularly when dealing with authoritarian states.”