HANOI, Vietnam — President Donald Trump cut short his summit with Kim Jong Un on Thursday, rejecting the North Korean leader's offer to dismantle a major nuclear complex in exchange for the removal of U.S. economic sanctions.

Trump said the U.S. wanted more concessions from Kim and that talks would continue. But the president wouldn't commit to holding a third summit after two high-profile meetings have failed to produce a concrete agreement on rolling back North Korea's nuclear weapons program.

"Sometimes you have to walk," Trump told a news conference here in the Vietnamese capital before departing for Washington on Air Force One. "This was one of those times."

The summit's collapse represented a setback for Trump, who watched his made-for-TV diplomacy eclipsed by the congressional testimony of his former lawyer, Michael Cohen, who suggested at a House hearing Wednesday that the president had violated federal laws with payoffs to conceal alleged extramarital affairs.

Asked about Cohen's testimony at the news conference, Trump said his former confidant "lied a lot."

"I think having a fake hearing like that and having it in the middle of this very important summit is really a terrible thing," Trump said.

Trump indicated that Kim was willing to agree to dismantle Yongbyon, a sprawling nuclear complex that includes North Korea's only plutonium reactor as well as facilities to produce highly enriched uranium.

But in exchange, Trump said, Kim wanted U.S. sanctions "lifted in their entirety, and we couldn't do that."

Secretary of State Michael R. Pompeo elaborated that shutting down Yongbyon still "leaves missiles, warheads and weapons systems."

Trump said the U.S. wanted North Korea to give up secret facilities other than Yongbyon, adding: "We know every inch of that country." Analysts relying on satellite images have said North Korea has at least one other facility to produce uranium.

When it became clear that the two sides were too far apart to reach an agreement, the White House scrapped plans for a working lunch and canceled a scheduled signing ceremony. (It had never been clear what was going to be signed.)

Trump's motorcade departed the meetings at Hanoi's Hotel Metropole shortly before 1:30 p.m. local time, more than an hour earlier than planned.

Trump was under pressure before the Vietnam meetings to show progress in his outreach to Kim's enigmatic dictatorship. Last June's summit in Singapore yielded only vague promises from Kim to denuclearize, with no definition of what that meant and no road map to reach that goal.

But this week's meetings, which began with a dinner Wednesday, failed even to produce the mostly symbolic concessions that many observers had expected, such as an agreement to open diplomatic liaison offices _ a step toward establishing normal ties _ or declaring an end to the Korean War.

The summit did elevate Kim for the second time in nine months, placing him side by side with the U.S. president on the world stage _ their faces painted on city walls and screened onto souvenir T-shirts, their country's flags flying together from lampposts, the imagery of their easy interactions broadcast live around the world.

The once-reclusive autocrat arrived in Vietnam by train, preferring the long two-day journey from Pyongyang to flying. He will leave having been further normalized as a statesman without making new concessions.

The sudden breakdown in talks Thursday came just hours after Trump and Kim demonstrated a growing chumminess and expressed optimism about making actual progress.

Asked by a reporter if he felt confident, Kim _ who had never before answered questions from a reporter _ said, "I wouldn't say that I'm pessimistic."

Later, Kim responded to another question about whether he was willing to denuclearize. "If I was not, I wouldn't be here," he said.

Trump, with reporters and cameras in the room, lauded Kim: "That might be the best answer you've ever heard," he told the media.

A few hours later, after the summit's premature conclusion, Trump made it clear that he is no longer demanding Kim's "complete and verifiable denuclearization."

"I don't want to put myself in that position from the standpoint of negotiation," Trump said at Thursday's news conference _ a remarkable departure from Pompeo's statement last year that "the complete and verifiable and irreversible denuclearization of the Korean peninsula is the only outcome that the United States will accept."

Trump said Kim assured him that North Korea would continue a moratorium on missile tests that has been in place since April 2018. That followed a provocative series of nearly 23 North Korean missile launches over 10 months, including an intercontinental ballistic missile that landed in Japanese territory.

"I trust him, and I take him at his word," Trump said. "I hope that's true. But in the meantime, we'll be talking."

Trump repeatedly emphasized his warm relationship with Kim, the head of a family dictatorship that is accused of grave human rights violations.

He also accepted Kim's claim that he was unaware of the fate of Otto Warmbier, an American college student who was imprisoned by North Korea for 17 months and was in a coma when he was released in June 2017. Warmbier died days later.

"Those prisons are rough, they're rough places and bad things happened," Trump said. But, he added, Kim "felt badly about it. ... He tells me that he didn't know about it, and I will take him at his word."

Trump's willingness to accept Kim's denial was strikingly similar to his credulity with other autocrats. Last July in Helsinki, Finland, he accepted Russian President Vladimir Putin's denial of 2016 election interference over the conclusions of U.S. intelligence officials. And in November, he again refused to accept his own government's findings about Saudi Arabia's crown prince having orchestrated the murder of dissident Saudi journalist Jamal Khashoggi, telling reporters that it was impossible to determine the prince's involvement.

At his news conference in Hanoi, Trump called mainly on foreign reporters, passing over several members of the White House press corps who were more likely to have asked additional questions about Cohen's allegations.

Shortly after taking off from Hanoi, Trump called South Korean President Moon Jae-in, who has nudged Trump along his path of engagement with Kim. A spokesman for Moon tried to strike a hopeful note, saying it was "meaningful progress for Trump to have publicly expressed a willingness to lift sanctions in exchange for denuclearization, and that South Korea would work to keep the momentum going in U.S.-North Korea talks.

Victor Cha, Korea chair at the Center for Strategic and International Studies, a Washington think tank, tweeted that the summit was "an outright failure" _ but said Trump "made the right decision to push for more than minimal steps and take no deal over a bad deal."

Cha added: "Not clear where it goes from here when leaders can't agree."

Others said talks between the two countries seemed likely to continue at the working level, even if prospects for another Trump-Kim summit were unclear.

Christopher Green, a senior advisor to the International Crisis Group, said that while the summit was a setback, North Korea had probably staked out a maximum position on sanctions removal that it didn't expect Trump to accept.

"Both parties likely concluded that it would be all right to walk away this time, looking tough for their respective domestic audiences by going home empty-handed," Green said. "It may be frustrating for advocates of peace on the Korean peninsula, but it won't do the two leaders any great harm."