President Lee Jae-myung and Trump have both faced attempts on their lives; Lee even had to undergo surgery after being stabbed in the neck.

The new South Korean administration will likely make efforts to buy time for U.S. trade talks, as it studies the negotiations of bigger neighbours Japan and China for leverage, according to sources familiar with the ruling party's thinking.

Korea watchers want to know, as the American leader spends an hour and a half on the phone with the Chinese party boss, Xi Jinping.