It was unclear if Mr. Assad had promised a concrete visit or had merely suggested it as a possibility out of diplomatic politeness.

Analysts questioned whether the report represented the true intentions of Mr. Assad, given that it gave no date or details. David Maxwell, associate director for the Center for Security Studies at Georgetown University, said that Ambassador Mun may have misunderstood Mr. Assad, or his aides may have misreported what they thought the Syrian leader said.

Given the looming summit with Mr. Trump, Mr. Maxwell said he was puzzled by the North’s announcement of a possible visit from the Syrian leader, who has been entangled in a bloody civil war and condemned by the West for the use of chemical weapons against his own citizens.

“I am struggling to figure it out and trying to put aside my Western bias and look at from Kim Jong-un’s perspective,” Mr. Maxwell said. “If they think it enhances their legitimacy, then they certainly don’t have a good understanding of the international community, and certainly what the U.S. is going to think about it.”

United Nations experts accused North Korea of shipping materials to the Syrian government that could be used in the production of chemical weapons during the brutal civil war it has been fighting against rebels since 2011.

The materials were part of at least 40 shipments that North Korea made to Syria between 2012 and 2017 that could be used for both civilian and military purposes, the United Nations report said. North Korean technicians had also been seen working at chemical weapons and missile facilities in Syria.

Mr. Trump has twice ordered airstrikes against Syria to punish Mr. Assad for suspected chemical attacks on civilians, saying the Syrian president had committed “crimes of a monster.”