WASHINGTON – The United States and North Korea launched an urgent backstage mission on Sunday to resurrect a summit between their leaders until June 12 to develop a common agenda and deep skepticism about the odds Achieving a framework for a lasting nuclear agreement in such a short time.
Technical and diplomatic experts from the United States paid a rare visit to North Korea to meet with their colleagues, American officials said Sunday. Before a summit, the American team, led by Sung Kim, an experienced diplomat, is seeking detailed commitments from North Korea's leader Kim Jong-un about his regime's willingness to abandon its nuclear weapons program.
In a Tweet Sunday night, President Trump confirmed the meeting in the North Korean part of Panmunjom, a "ceasefire village" inthe demilitarized zone that separates the two Koreas. He also expressed his government's renewed optimism about the meeting and added further words to the conciliatory language that both sides have used since canceling the scheduled meeting in a bitter letter to Mr. Kim on Thursday.
"I truly believe that North Korea has brilliant potential and will someday be a great economic and financial nation" Mr. Trump wrote on Twitter after a second straight day of golf at his club in Virginia. "Kim Jong Un agrees with me. It's going to happen!"
White House officials said that Joe Hagin, a White House deputy chief of staff, is directing a separate delegation in Singapore where the summit should take place for logistics work out: when the various meetings would take place, how much would be open to the press, which officials would be in the courtroom, how would one deal with security concerns
The simultaneous negotiations in the DMZ and in Singapore signaled an accelerated effort by governments in both Countries to make the factual and practical preparations needed to get the meeting going again.
Such problems would typically be dealt with through a well-established diplomatic process of lower-level negotiations that would normally take months, if not years, between the leaders of two nations. But Mr. Trump short-circuited this process in March when he abruptly accepted an invitation to meet with Mr. Kim.
Now that he has abruptly canceled the summit, Mr. Trump, whether he likes it or not, has set in. I will start a more normal series of discussions to lay the groundwork for an agreement on North Korea's nuclear weapons program before decides whether a meeting should take place between the two leaders.
The schedule is still extremely short. Mr. Trump's desire to keep June 12 as a possible date for a summit means that officials on both sides are rushing to see if the necessary preparations can be completed within a few days. Veteran negotiator said it was unclear whether the two sides could get enough work done to make a meeting possible.
"The president says he will not go until there is a substantial consensus, so the question is, is it time to reach that kind of agreement?" Said Joseph Y. Yun, a former North Korea chief negotiator in the State Department, which withdrew in part because of his frustration at the diminished role of his agency. "Right now, the summit is teetering on whether we're making progress on these things."
Two high-ranking republican MPs on Sunday expressed their grave concern over the prospects for a successful summit in just over two weeks and warned that Mr. Kim would never agree to give up the nuclear weapons his country has been developing for decades.
"I'm convinced that he does not want to denuclearize, he will not denuclearize," Senator Marco Rubio, Republican of Florida, said on ABC's "This Week." He dismissed Mr. Kim's good will demonstrations – including the release of American prisoners and the destruction of a nuclear test site – as meaningless.
"It's all a show," said Mr Rubio. "It's a show."
Sen. Jeff Flake, Republican of Arizona, reiterated Mr. Rubio's concerns. He said in NBC's "Meet the Press" that freezing the country's weapons program would be an advance, but added that "many of us were skeptical that North Korea would ever agree to total denuclearization."
Veterans of previous negotiations with North Korea also voiced concern on Sunday over the possibility that Mr Kim might demand that, in exchange for denuclearization, the United States must withdraw its "nuclear shield" protecting South Korea from opponents.
James R. Clapper Jr., former director of national intelligence under President Barack Obama, who spent part of his early intelligence career in South Korea, said on Sunday on CBS's "Face the Nation" that such a requirement could mean that the United States would have to agree not to fly nuclear-powered bombers "on the Korean peninsula or in operational proximity"
It is unclear whether Mr. Trump would ever agree to significant restrictions on the US nuclear arsenal  American officials have said that the discussions go well and provide the same optimistic assessment that Mr. Trump has given over the past 48 hours.
In brief remarks to reporters on Saturday night, the president said the lower level The negotiations are "very good," although he added his usual caveat, "We'll see what happens." On the Korean Peninsula, a surprise meeting between Mr. Kim and President Moon Jae-in from South Korea also brought some progress to a meeting.
Mr. Moon said that Mr. Kim wanted to discuss with Mr. Trump " complete denuclearization of the Korean peninsula".
"What he does not realize is how firmly he can trust the United States commitment to end hostile relations and provide security guarantees for his government should denuclearize it," Mr. Moon said at a press conference in Seoul on Sunday , the South Korean capital, the day after the meeting on the North Korean side of Panmunjom.
The answer to this question may depend on discussions between the lowest-level representatives of the two countries, a troubled process that can sometimes lead to disagreements and, in other cases, delay progress on the way to a meeting.  Government officials say they have no illusions that the team can now negotiate the details in North Korea to start dismantling the widespread nuclear, missile and biological weapons programs in North Korea – all of which were part of Foreign Minister Mike Pompeo's mission has recently agreed to the talks. In the case of the Iran Agreement, which met in 2015 with a detailed plan that Mr. Trump rejected as inadequate this month, the negotiations lasted more than two years.
But they can negotiate language and a timetable that Mr. Kim and Mr. Trump can agree on a framework for further negotiations. That alone would be a great achievement, as North Korea has rejected the idea of rapid denuclearization and wants a gradual approach.
The United States would also have to agree to changes that it might make, perhaps opening talks with a peace treaty that would formally end the Korean War. Another possible concession would be to give the North security guarantees that go beyond the assurances of past presidents that the United States would not seek to overthrow the present government.
But for veteran diplomats, US negotiating teams have said the kind of experience needed to at least craft the details needed for a summit.
The North Korea meeting on Sunday, first reported by the Washington Post reflected Mr. Trump's willingness to turn to diplomats and officials with decades of experience and close ties with ex-President George W. Bush. Mr. Hagin was a close Bush confidant and fixer in the White House, and Mr. Kim, the diplomat who led the American team, was tapped by Mr. Bush for a role similar to his new one.
A former US Ambassador To South Korea, Mr. Kim is not unfamiliar with the details of the North Korean nuclear program – or the delusions of the country.
A decade ago this month, he and a small team of Ministry of Foreign Affairs officials in Pyongyang were collecting plant records from a nuclear reactor in Yongbyon. He came across the DMZ with thousands of pages, the American experts of the C.I.A. and the Department of Energy used to calculate how much plutonium the country could produce.
Ultimately, North Korea blew up the cooling tower of this reactor as it blew up tunnel entrances to its nuclear test site last week. But within a few years, the reactor was back in operation. And now, Mr. Kim faces a much more complex program – one that has spawned more than 20 nuclear weapons, now uranium enrichment capabilities, and C.I.A.'s plutonium program and rockets. Estimates will be able to reach most American cities.
The news of any progress made by his team is likely to be sporadic, as there is no safe news from North Korea, officials said. Yun said that the goal for Kim was probably to develop a series of documents that both sides would have agreed upon and set out the three steps that North Korea would consider abolishing its nuclear weapons program.
The first step, he said, is an explanation of how far the North Koreans are prepared to carry out their weapons program. The second question is how and when the North Koreans would account to the United States for this process. And the third is to determine how the United States will confirm these allegations.
"It's a good group," said Mr. Yun. "It's a technical group, it's an expert group, and they know the problems, they know what to do."