Among the concerns are frustration that Trump has failed to secure a formal end to the Korean War while negotiating on nuclear disarmament; worries that the president is simply seeking a “trophy” for meeting with Kim and won’t be as engaged in the hard work to come; doubts about the “hubris” of the White House’s all-or-nothing approach to negotiating with Pyongyang, as opposed to the incremental process favored by many South Koreans; and dismay over why Trump would launch a trade war with China at a time when he needs Beijing’s help in keeping pressure on North Korea.

Most of those concerns relate, in some ways, to Trump’s personal characteristics — his unawareness of history, his short attention span — even as many South Koreans acknowledge that it was Trump’s very brashness that brought about the breakthrough in the first place.

“I’m concerned he may lose patience, and then just get out of this” said Dr. Jun Bong-Geun, a former policy adviser to South Korea’s minister of unification. “That could be possible, very possible.”