In cutting joint drills, Trump has given South Korea’s president what he wants. So why does Seoul look so uneasy?

At their first summit in August last year, South Korean president Lee Jae Myung told Donald Trump: “If you, Mr President, become the peacemaker, then I will assist you as the pacemaker.” This remark reflected Lee’s strategy of reducing military posturing and encouraging repeated peace overtures to revive dialogue with North Korea, despite Pyongyang’s consistent rejections, largely due to Seoul’s insistence on denuclearization. Fast forward to this week, Trump’s decision to cut joint military exercises with South Korea mirrors what Lee had promised during his term. The move is framed as a potential tool to revive dialogue with Pyongyang. Lee’s broader message is that South Korea should take more responsibility for its own defense and reduce reliance on others. On Tuesday, he also renewed calls for wartime operational control of the military and progress on South Korea’s nuclear submarine program. Trump delivered on the drills via social media, hours before they were to begin, in a blunt and discourteous manner typical of the president. This decision has inverted South Korea’s usual political lines, where the left-right divide is shaped more by attitudes toward North Korea—hawks versus doves, confrontation versus engagement—than by economic or social values. Reducing joint drills has long been advocated by some on the Korean left, but a right-wing US president imposing this policy on a center-left South Korean counterpart creates awkwardness for both sides. While some view the reduction as potentially useful for diplomacy, the primary concern in Seoul is that Trump is weakening a key pillar of deterrence, leaving South Korea with little say over decisions directly affecting its security. This could strain the alliance, which has been the bedrock of security on the Korean peninsula since the Korean War. The opposition conservative People Power party has called the decision a “security disaster” and warned of a return to “Korea passing,” a term used when Seoul feels sidelined in matters directly affecting it. Conservative newspapers have largely condemned the move as reckless. The influential Chosun Ilbo even blamed Lee’s government directly for inviting this situation. The left, however, did not share the sense of alarm. Hankyoreh, one of South Korea’s main progressive papers, criticized the unilateral and disrespectful manner of the decision but not its substance. Kyunghyang Shinmun took a more positive view, suggesting the cut could help create an atmosphere for dialogue with North Korea, provided deterrence remains intact. Reducing tensions with North Korea and creating space for dialogue are central to Lee’s agenda. The ruling party has remained quiet on the move but could face backlash from its base, which generally views Trump with suspicion or hostility. Beyond domestic politics, the episode deepens doubts about Washington’s commitment to its allies, a concern that has been growing since Trump’s first term. Prof. Jaechun Kim, teaching international relations at Sogang University, argues that trust is the foundation of any alliance, and Trump’s transactional approach reinforces the impression that America’s obligations are increasingly seen through a transactional lens. This could shape how South Koreans judge US reliability long after Trump leaves office. Additionally, the issue of nuclear deterrent strengthens public support for an independent deterrent among South Koreans and their neighbors, which has hovered around or over 70% in recent surveys. Prof. Kim expects Pyongyang to welcome any sign of friction within the alliance but doubts it views improving relations with Washington as a priority, given stronger backing from China and Russia compared to during Trump’s first term. The irony, he says, is that US policies intended to reduce American burdens may ultimately strengthen calls for independent nuclear deterrents among US allies.