SEOUL, South Korea — Secretary of State Mike Pompeo said he had a “good trip” to North Korea, meeting with its leader, Kim Jong-un, on Sunday and making progress in diplomatic efforts to denuclearize the country.
Mr. Pompeo posted a photo of himself with Mr. Kim on his Twitter account.
“Had a good trip to #Pyongyang to meet with Chairman Kim,” he wrote. “We continue to make progress on agreements made at Singapore Summit,” referring to the meeting between Mr. Kim and President Trump in June.
In Pyongyang, Mr. Pompeo held a two-hour meeting with Mr. Kim, followed by a 90-minute luncheon hosted by the North’s leader.
“It’s a very nice day that promises a good future for both countries,” Mr. Kim said through an interpreter from the dining table.
Mr. Pompeo said: “We had a great, great visit this morning. President Trump sends his regards. And we had a very successful morning, so thank you.”
An American official who accompanied Mr. Pompeo said on Sunday that the trip was “better than the last time,” referring to the secretary’s trip there in July, according to a pool report. But the official, who was not identified, added, “It’s going to a long haul.”
Later Sunday, Mr. Pompeo arrived in South Korea, where he planned to meet with President Moon Jae-in and other officials.
Mr. Pompeo was on his fourth visit to Pyongyang on Sunday in hopes of a breakthrough in stalled negotiations on the terms of denuclearizing North Korea. His meeting with Mr. Kim provided him with an opportunity to ensure that the two nations are on the same page in their understanding of Mr. Kim’s commitment to work toward the “denuclearization of the Korean Peninsula.”
Mr. Pompeo also sought to find out whether a second summit meeting between Mr. Kim and Mr. Trump was possible and if so, what could result from such a meeting.
Harry J. Kazianis, director of defense studies at the Washington-based Center for the National Interest, called the meeting “a make-or-break event for U.S.-North Korea relations” with an enormous downside “if it were to go badly.”
Mr. Kim and Mr. Trump met for the first time in June in Singapore, and it was there that Mr. Kim committed to “work toward the complete denuclearization of the Korean Peninsula.” In return, Mr. Trump promised North Korea security guarantees and “new” relations.
But talks over denuclearization have since stalled. And Mr. Trump’s critics have charged that his eagerness to claim progress in resolving the North Korean nuclear crisis, one of the most urgent problems he inherited from the Obama administration, has blinded him to the country’s deceptive nature.
In July, when Mr. Pompeo made his last trip to Pyongyang, Mr. Kim wouldn’t even meet with him, and the North accused Washington of making a “unilateral and gangster-like demand for denuclearization.” When Mr. Pompeo planned another trip to Pyongyang in August, Mr. Trump canceled it at the last minute when it was apparent that no major concession was expected from the North in relinquishing its nuclear arsenal.
Mr. Moon of South Korea then stepped in as a mediator, flying last month to Pyongyang for his third summit meeting with Mr. Kim.
In an internationally televised joint news conference with Mr. Moon, Mr. Kim said he wanted to make the Korean Peninsula “free of nuclear weapons and nuclear threat.” He also offered to dismantle missile-test facilities and invite international experts to watch for transparency.
He also proposed to “permanently dismantle” the Yongbyon nuclear complex, the North’s main center for producing fuel for nuclear bombs — but only if Washington took “corresponding” measures.
Mr. Trump has since sounded effusively optimistic, mentioning “beautiful letters” he said Mr. Kim wrote to him and saying that he was ready to meet with Mr. Kim soon. He even said he and Mr. Kim “fell in love.”
North Korean officials who dined with members of Mr. Pompeo’s entourage in a separate room said that it would be great if Mr. Trump visited Pyongyang for a second summit meeting with Mr. Kim.
They also asked American officials about the midterm elections in the United States. One of them, Kim Song-hye, called Mr. Trump “generous” and “a leader,” and said the two countries “wouldn’t be here without Trump.”
But there is no sign that North Korea has changed its decades-old negotiating strategy, which often involves making pledges that it fails to carry out.
Speaking to the United Nations General Assembly last month, its foreign minister, Ri Yong-ho, said that although his government’s commitment to denuclearization was “solid and firm,” there was “no way” his country would unilaterally disarm unless Washington took steps to demonstrate that it is no longer a threat.
Noting continuing American hostility, Mr. Ri cited Washington’s campaign to escalate sanctions against the North and its refusal to declare an end to the Korean War, which was only halted with a truce.
But Washington stressed that it will keep sanctions as leverage until North Korea denuclearizes. It also insisted that the North first start the denuclearizing process by submitting a full inventory of its nuclear program and agreeing to intrusive inspections to verify that no warhead or fissile materials are hidden.
Past nuclear talks between North Korea and the United States had fallen apart over how to verify that the North had owned up to all its nuclear activities.
If the United States insisted that North Korea provide a full nuclear inventory and submit to time-consuming verification first, the negotiations will derail again as they did in the past, some analysts warned.
“Going down that road is a dead end,” Siegfried S. Hecker, a former director of the Los Alamos National Laboratory, who has visited North Korea several times, said during a lecture in Seoul on Sept. 27.
Instead, he said the two sides must start with risk-reduction steps, like dismantling the Yongbyon complex, and leaving the difficult and time-consuming verification to a later phase of denuclearization, when the two sides have gained mutual confidence in each other.
Foreign Minister Kang Kyung-wha of South Korea also raised the idea of leaving inspection and verification to a later stage in remarks he made during an interview with the national broadcaster KBS on Sept. 21.