WASHINGTON — President Trump opened the door on Tuesday to a phased dismantling of North Korea’s nuclear weapons program, backing away from his demand that the North’s leader, Kim Jong-un, completely abandon his arsenal without any reciprocal American concessions.
The president’s hint of flexibility came after North Korea declared last week that it would never agree to unilaterally surrender its weapons, even threatening to cancel the much-anticipated summit meeting between Mr. Kim and Mr. Trump scheduled for next month in Singapore.
Mr. Trump’s statement seemed less a policy shift than an effort to preserve his date with Mr. Kim. But while the gesture may avoid a swift rejection by Mr. Kim, it shows that Mr. Trump is willing to give up what for months has been his bedrock position in dealing with the North. And it demonstrates that three weeks before the June 12 meeting, the White House is still groping for a strategy to negotiate with a reclusive, suspicious nuclear-weapons state.
The scale of North Korea’s program, he said, would make it difficult to dismantle it in a single step. “It would certainly be better if it were all in one,” Mr. Trump said. “Does it have to be? I don’t think I want to totally commit myself.”
The president’s comments, delivered as he welcomed President Moon Jae-in of South Korea to the Oval Office, were the latest move in a battle of wits between Mr. Trump and Mr. Kim, two leaders who both clearly want to talk but recognize the deep gulf that separates them.
Mr. Trump expressed continued enthusiasm for the meeting, saying he believed it could usher in a new era of prosperity for North Korea and safety for Mr. Kim. But he acknowledged that after North Korea’s shift in tone, it could be delayed.
“There’s a very substantial chance that it won’t work out, and that’s O.K.,” Mr. Trump told reporters, as Mr. Moon listened. “That doesn’t mean it won’t work over a period of time. But it may not work out for June 12.”
“There are certain conditions we want to happen,” he added. “I think we’ll get those conditions. And if we don’t, we won’t have the meeting.”
Secretary of State Mike Pompeo, who has met twice with Mr. Kim to make arrangements for the meeting, expressed optimism that it would still take place. But he warned that there would likely be more twists and turns before the two leaders shook hands in Singapore.
Mr. Trump has done little to hide his excitement about that prospect. The White House has even issued a commemorative coin for the meeting that depicts the two men, in profile, facing each other, and refers to Mr. Kim as the “Supreme Leader.” But inside the White House, one official said, there was confusion about what will happen on June 12 — or whether a meeting will happen at all.
Mr. Trump said he detected a change in Mr. Kim after he met China’s president, Xi Jinping, this month in the coastal Chinese city of Dalian. He suggested that Mr. Xi, whom he described as a “world-class poker player,” encouraged Mr. Kim to harden his approach to the United States, in part to gain leverage in trade negotiations between China and the United States.
“There was a different attitude by the North Korean folks after that meeting,” Mr. Trump said. “I can’t say that I’m happy about it.”
The threatening words between Pyongyang and Washington have also raised the pressure on Mr. Moon, who has acted as a kind of go-between for Mr. Trump and Mr. Kim. His diplomacy set the stage for the Singapore summit meeting, and he has urged Mr. Trump to push for a historic breakthrough with the North, saying that such an achievement would make him a candidate for a Nobel Peace Prize.
Turning to Mr. Moon, Mr. Trump asked him whether he believed that Mr. Xi was influencing Mr. Kim. Mr. Moon deflected the question, though he conceded there was skepticism in the United States about the prospects for a successful negotiation. He said Mr. Trump’s participation set this process apart from previous ones.
“The person who is in charge is President Trump,” Mr. Moon said. “I have every confidence that he will be able to make a historic turnaround in this sense.”
Though Mr. Moon’s visit had been scheduled for weeks, Mr. Trump called him on Saturday, ahead of his visit, suggesting the depth of uncertainty he feels about the harsh words from Pyongyang. North Korea objected particularly to John R. Bolton, Mr. Trump’s new national security adviser, who said recently he viewed Libya as a template for negotiating the denuclearization of North Korea.
Mr. Trump subsequently disavowed Mr. Bolton’s remarks, acknowledging that Libya’s voluntary disarmament in 2003 did nothing to protect its leader, Col. Muammar el-Qaddafi, from being killed by his own people less than a decade later in the upheavals that swept the Arab world.
On Tuesday, Mr. Trump went out of his way to guarantee Mr. Kim’s safety. “He will be safe. He will be happy. His country will be rich,” the president said.
Analysts noted it was not clear how the United States would protect Mr. Kim from a domestic uprising like the one that convulsed Libya.
Mr. Moon sought assurances of his own — not least that the United States will maintain American troop levels in South Korea, regardless of its negotiation with Mr. Kim. Mr. Trump has long expressed a desire to withdraw troops, and the National Security Council has asked the Pentagon to prepare options for changing levels of military forces.
Still, South Korean officials said Mr. Moon delivered an essentially upbeat message to Mr. Trump.
“We believe there is a 99.9 percent chance the North Korea-U.S. summit will be held as scheduled,” Mr. Moon’s national security adviser, Chung Eui-yong, said to reporters traveling to Washington. “But we’re just preparing for many different possibilities.”
Most analysts said they believed the meeting would still happen because both leaders were so invested in it.
“But the notion that this would be an easy win, with North Korea turning over a new leaf and trading in its nukes for the embrace of the free world, is dissipating in the president’s mind,” said Victor D. Cha, a Korea expert at Georgetown University who was briefly considered as ambassador to Seoul by the Trump administration. “There are no fairy tale endings with North Korea.”
Jung Pak, a former C.I.A. analyst now at the Brookings Institution, said, “In effect, President Trump is getting a mini-lesson in talking to the North Koreans even before he talks to the North Koreans.”
Mr. Trump’s flexibility on when and how North Korea would dismantle its program, some analysts said, was a welcome recognition of reality. The idea of packing up North Korea’s sprawling nuclear program and flying it out of the country on American military transport planes was always far-fetched.
“Trump believed he was going to get complete denuclearization, and now he realizes he’s not,” said Michael J. Green, senior vice president for Asia at the Center for Strategic and International Studies. “So now they’re trying to find a credible way to claim this summit will lead to denuclearization.”
A spokesman for Mr. Moon said he and Mr. Trump had agreed to join efforts to make sure the summit meeting came off as planned. The two leaders, the spokesman said, discussed “ways to address the sense of insecurity.”
“North Korea could have after it declared complete denuclearization for the first time,” he said.
Other experts in South Korea said there were still high hopes for the Trump-Kim encounter, and that the White House should not get rattled.
“There may be a sense here that the Trump team is overreacting to North Korea’s pushback last week and losing sight of the big picture,” said John Delury, an associate professor of Chinese studies at Yonsei University in South Korea.
“Of course gaps remain in terms of negotiating peace and denuclearization of the Korean Peninsula,” Mr. Delury said. “That’s the reason a negotiation is necessary.”