South Korean President Lee Jae-myung is pulling out all the stops to improve ties with Beijing. During a four-day state visit to China in early January, he snapped a selfie with Chinese leader Xi Jinping on a new Xiaomi smartphone that his hosts had given him, told an audience that he sought to “upgrade” Chinese-South Korean relations, and signed more than a dozen agreements on topics as varied as trade, climate, and transportation. This followed the two leaders’ long conversation on the sidelines of the Asia-Pacific Economic Cooperation (APEC) forum in South Korea in early November, where Lee regally welcomed Xi with an honor guard and a welcome banquet to mark the Chinese leader’s first state visit in years. 

For Lee, cozying up to Xi can stabilize the relationship with South Korea’s largest trade partner and open new channels of influence over rival North Korea, which depends on China economically. Xi, for his part, seems amenable to Lee’s overtures: after frosty relations with Yoon Suk-yeol, the former South Korean president, warmer ties with Lee can boost Beijing’s position in its strategic competition with Washington by helping pull South Korea away from Japan and the United States. But the bonhomie is unlikely to last.

In mid-November, just two weeks after laying out the red carpet for Xi at APEC, Lee and U.S. President Donald Trump reached an unprecedented deal to cooperate on nuclear-powered submarines. Although many details are still unclear, the agreement will allow Seoul to fulfill a long-standing goal of upgrading its fleet, either by providing U.S. technology and fuel for South Korean nuclear submarines or by encouraging South Korea to develop its own. Seoul would use these submarines to track North Korean vessels—but also those of China, a reality that will incense Beijing.

So far, this bombshell announcement has not provoked a reaction from Beijing. It’s possible that the Chinese leader was unprepared for the surprise move or that Xi’s spat with Japan over Prime Minister Sanae Takaichi’s comments about the importance of Taiwan’s security to Tokyo has made Lee a useful friend at this moment. But Beijing will not forget about the nuclear submarine deal. China, in response to other geopolitical slights, has sanctioned at one point or another almost every Korean product, ranging from music to cosmetics to television shows to kimchi. Xi did not seem convinced by Lee’s explanation that Seoul needed the new military capability to counter the expanding North Korean nuclear threat. Instead, during Lee’s visit to Beijing, Xi warned the South Korean president to make the “correct strategic choice,” a cryptic threat that Lee brushed aside to minimize any appearance of discord as he tries to repair ties.

When Beijing eventually turns up the economic heat on Seoul, South Korea cannot stand up to China alone. Instead, Japan, the United States, and other regional partners should work with South Korea to fend off Beijing’s severe economic coercion. Together, past and future targets of China’s economic bullying can amass enough economic leverage to fight back against such pressure tactics and liberate their foreign policy decision-making from under Beijing’s thumb.

South Korea is no stranger to Chinese coercion. In 2016–17, Seoul allowed the United States to place a Terminal High Altitude Area Defense (THAAD) battery in Seongju, South Korea, to defend against North Korean ballistic missiles. Beijing opposed this move because it claimed that THAAD’s radar systems could penetrate deep into Chinese territory; it responded by imposing massive sanctions against South Korea’s entertainment, cosmetics, and tourism industries. A targeted pressure campaign against Lotte, the South Korean conglomerate that originally owned the land where the THAAD system was placed,........

© Foreign Affairs