Lee Jae-myung is seeking closer relations with the PRC. I view it as part of the missing context to this spat. These events preceded the US administration's actions.
https://world.kbs.co.kr/service/news_view.htm?Seq_Code=18451...
https://world.kbs.co.kr/service/news_view.htm?Seq_Code=18451...
But also likewise, Korea holds historic antagonism towards China, arguably just as much as it does to Japan. Most of the population would hate such a relationship, and despite some in the left thinking otherwise, most South Koreans still see the US as the favorable partner over China.
But with China’s continued rise, and the US seemingly evolving (irreversibly?) into the MAGA Empire, that perception isn’t guaranteed to never change either. The PRC isn’t doing itself much favors in courting its neighbors, so it’ll become a game of who is worse.
The same can be said with the Korean liberal/left parties in general, to varying degrees.
So while he is currently presenting himself as more of a centrist and pragmatist, it remains to be seen if he remains so.
Conspiracy theorists on the Korean right claim it is Trump that is playing into LJM’s hand in providing an excuse to pivot to the PRC.
In fact, France is the US' oldest ally and its best known president in the 20th century is largely remembered for making sure to remain militarily independent from the US.