Mr. Kim, for his part, has balked at dealing with anybody but Mr. Trump. He rebuffed Secretary of State Mike Pompeo, whom Mr. Trump put in charge of the negotiations, and told the president in a letter that he preferred to deal directly with him.
There have been no substantive working-level negotiations between the two sides since last fall. While Mr. Pompeo emerged from a meeting with Mr. Kim in October declaring that the North Korean leader told him “he’s ready to allow” inspectors into a nuclear testing site that the North had blown up, that inspection has yet to happen.
Larger issues of inspection will hang over the next meeting as well. One subject under discussion with the North, according to officials of several countries briefed on the talks, is whether the country would “freeze” its nuclear fuel and weapons production during negotiations, so that the country’s arsenal does not grow while talks drag on.
“But that would require highly intrusive inspections, across the country,” said Jung Pak, a former senior C.I.A. analyst now at the Brookings Institution. “Previous negotiations have fallen apart because of our insistence on those inspections. And who is going to take North Korea’s word on whether it is truly freezing its program?”
Some analysts and diplomats said they worried that by agreeing so readily to another meeting, Mr. Trump was inviting the same situation as in Singapore — a press extravaganza that produces little in the way of concrete achievements.
“You have to be afraid that we are playing into North Korea’s hands,” said Joseph Y. Yun, a former State Department official who has negotiated with the North. “They want to wait, and have as much time as possible elapse when they don’t do anything significant to denuclearize, and become accepted regionally and globally as a nuclear state.”
The risk was even greater, some said, because of the multiple political and legal challenges facing Mr. Trump, from the government shutdown to the investigation of ties between his presidential campaign and Russia.