For more than a year, U.S. President Donald Trump was confident he could personally achieve a Herculean feat of diplomacy: Convincing a country to give up its nuclear weapons. He would do it, he believed, through the sheer strength of his bargaining skills.

But those efforts unravelled abruptly at a Vietnam hotel Thursday, when he walked away from talks with Kim Jong-un. The North Korean dictator, Mr. Trump said, had demanded the United States completely lift sanctions on Pyongyang without Mr. Kim giving up his nuclear arsenal in exchange.

Mr. Trump drew plaudits for making no apparent concessions. But he took fire for his seeming naiveté in believing such complex international negotiations would work differently for him than they have for everyone else who has previously tried to curb Pyongyang’s weapons programs.

After a two-hour one-on-one meeting with the North Korean leader and a longer sit-down with officials on both sides, Mr. Trump cancelled a planned deal-signing.

The President told reporters Mr. Kim was willing to close Yongbyon, a major nuclear facility that produced material for the country’s bomb tests, but refused to shut down other nuclear sites or get rid of his existing warheads and missiles.

“They wanted the sanctions lifted in their entirety, and we couldn’t do that. They were willing to denuke a large portion of the areas that we wanted,” he said. “But they weren’t willing to do an area that we wanted.”

North Korea has as many as 60 nuclear devices, according to an estimate last year by the South Korean government. In 2017, Mr. Kim’s military tested an intercontinental ballistic missile capable of striking Washington.

North Korean Foreign Minister Ri Yong-ho later insisted Pyongyang had not asked for all sanctions to be lifted. Rather, he claimed, North Korea offered to shutter Yongbyon “in the presence of U.S. experts” in exchange for an end to some sanctions on the country’s civilian economy.

“If the U.S. removed partial sanctions … we will permanently and completely dismantle all the nuclear-material production facilities,” he told reporters.

The President has regularly chided previous administrations for failing to get North Korea to give up its nuclear weapons. After first threatening Mr. Kim with nuclear war, Mr. Trump pulled an about-face last year and became the first U.S. President to agree to meet with a North Korean leader. That summit in Singapore yielded a vague agreement to work toward denuclearization.

Secretary of State Mike Pompeo and Stephen Biegun, the U.S. point person on North Korea, have worked in the intervening months to make some sort of tangible progress in talks with Pyongyang.

Speaker Nancy Pelosi, the top Democrat in Congress, said Thursday that she was “glad that the President walked away from” a bad deal with Pyongyang. But she argued Mr. Trump had already given Mr. Kim a propaganda coup by treating him as an equal.

“It took two meetings for him to realize that Kim Jong-un is not on the level,” Ms. Pelosi said at the Capitol. “He was a big winner, Kim Jong-un, in getting to sit face to face with the most powerful person in the world.”

Carla Robbins, a national-security expert at the Council on Foreign Relations, said Mr. Trump’s mistake was to meet with Mr. Kim when basic issues – such as what each side actually means by “denuclearization” – apparently had not been sorted out beforehand.

“This is pure Trump. ‘I’m the deal-maker, I’m going to get everybody in the room and I’m going to bend them to my will.’ And it didn’t work,” she said.

Ms. Robbins said Mr. Trump also telegraphed desperation for a deal to Mr. Kim by showing deference to his authoritarian ways: At the Hanoi summit, for instance, the Americans agreed to kick U.S. media out of the hotel where Mr. Kim was staying.

And at his closing news conference, Mr. Trump said he believed Mr. Kim’s denials of involvement in the torture of Otto Warmbier, a U.S. college student who died in 2017 after he was arrested in North Korea. “He tells me he didn’t know about it, and I will take him at his word,” Mr. Trump said. “Those prisons are rough places.”

Jon Wolfsthal, senior adviser to anti-nuclear weapons group Global Zero, contended Mr. Trump could have made an incremental deal by agreeing to limited sanctions relief in exchange for the closing of Yongbyon.

“What we saw was a negotiation that played out at a working level, then the U.S. went in at the last minute and moved the goalposts,” said Mr. Wolfsthal, who was former president Barack Obama’s top adviser on nuclear non-proliferation.

In the immediate aftermath, the path forward was unclear.

Naoko Aoki, a nuclear-security fellow at the RAND Corporation, said the bright spot is that neither side has given up on future talks.

“This has been a leadership-led process from the beginning, and ultimately it will continue as long as the two leaders want [it] to,” she said. “Reducing North Korea’s nuclear threat is going to take time.”

Mr. Kim himself sounded optimistic in the hours before the summit collapsed, when he took the rare step of answering reporters’ questions during a pair of photo ops with Mr. Trump. Asked if he was ready to denuclearize, he said yes.

“If I’m not willing to do that,” he said, “I won’t be here right now.”

The Globe and Mail, February 28, 2019