It was a bolt from the blue. Hours after President Trump and Kim Jong-un appeared to be on the cusp of a historic denuclearization agreement and the North Korean leader told a US journalist that he had “a feeling that good results will come,” the bilateral peace summit in Hanoi ended abruptly, with both leaders walking out before signing anything.

The surprise ending came after a day and a half of talks that focused on an emerging deal in which North Korea would have shut down its massive Yongbyon plutonium and uranium facility—the crown jewels of its nuclear program—in return for relief from the US and UN sanctions that have crippled its economy. There was also hopeful talk of a formal declaration to end the Korean War and the opening of liaison offices in Pyongyang and Washington.

But Trump apparently decided to walk away without even an interim agreement because, in his version of events, Kim demanded a total lifting of sanctions in return for his country’s concessions. “It was about the sanctions,” Trump explained to a startled media at a press conference called after the US and North Korean delegations canceled what would have been an elaborate luncheon and signing ceremony.

“Basically, they wanted the sanctions lifted in their entirety, and we couldn’t do that,” Trump added. “They were willing to denuke a large portion of the areas that we wanted, but we couldn’t give up all of the sanctions for that.” But he noted that Kim had pledged not to resume testing of his weapons or missiles, a critical decision that prevents the North from developing a full nuclear-attack capability.

Standing beside Trump, Secretary of State Mike Pompeo added that it wasn’t all a wash. “We made real progress” during the 36 hours of talks, he told the press. “Unfortunately, we didn’t get all the way” to “something that ultimately made sense for the United States of America.” But he expressed optimism about the talks continuing, saying he was hopeful the US and North Korean negotiating teams will soon get back together “and continue to work out what’s a very complex problem.”

The decision to terminate the talks was a blow to South Korean President Moon Jae-in, who had told Trump before the summit that his country was willing to act as an economic bridge with North Korea as a way to get to a final agreement. Moon has also urged that the US and the UN relax some sanctions so North and South can continue their plans, spelled out in their bilateral summits last year, to deepen economic cooperation by linking their roads and railroads, reopening the Gaesong Industrial Zone just north of the DMZ, and other steps.

Those projects have reached a limit with the sanctions. The collapse of the US–North Korea talks is “terrible for Moon Jae-in, who cannot pursue more than ceremonial inter-Korean cooperation for the foreseeable future,” Chad O’Carroll, the CEO of the Korea Risk Group and an editor at its NK News, tweeted from Hanoi just after the talks ended.

Kim Eui-kyeom, Moon’s spokesperson at the Blue House, said in statement that Seoul “regrets” the fact the Trump and Kim couldn’t reach an agreement. He added that the discussions of sanctions relief in relationship to denuclearization shows that the two countries have brought their discussions “to another level.”

But in a sign that South Korea may become more involved in the US discussions with the North, Trump asked President Moon in a telephone call to “actively” mediate his dialogue with Kim. Many Koreans now expect Moon to hold another summit with Kim, as he did when the US talks with the North appeared on the verge of collapse in 2018.

Some analysts said it was too early to gauge what went down based on Trump’s version. “Exactly what happened is unclear and we will need to wait for the dust to settle,” Joel Wit and Jenny Town of the 38 North think tank wrote on Thursday morning. “It’s hard to believe that Kim Jong Un wanted all sanctions lifted in return for just dismantling Yongbyon. He must have known going in that was a non-starter.”

It didn’t take long for the North Korean story to emerge. In a midnight press conference in Hanoi, North Korean Foreign Minister Ri Yong Ho, who was deeply involved in the talks, directly contradicted the US president and said the North only sought partial sanctions relief in exchange for closing Yongbyon.

When Washington demanded a further step beyond Yongbyon, he said, it became “crystal clear that the US was not ready to accept” the North Korean proposal. Choe Son Hui, the vice minister with years of experience dealing with the US government, added ominously, “I cannot guarantee that this opportunity will be offered to the US once more.”

There were also reports from South Korea that the presence at the talks of John Bolton, Trump’s aggressively hawkish national-security adviser, helped torpedo the talks.

In an interview with a Korean newspaper on Thursday, South Korea’s former unification minister, Chong Se-hyun, suggested that the summit was derailed by the “last minute” attendance of Bolton, who “added demands for North Korea to also report chemical and biological weapons” as well as their nuclear arsenal. In response, Chong said, the North Koreans “increased their demand for sanctions relief.”

Representative Ro Khanna, one of the most outspoken members of Congress on Korean issues, openly blamed Bolton in a series of tweets on Thursday morning. “I’m not shocked that Trump—with John Bolton at his side—has failed,” he wrote. He cited Bolton’s past statements in favor of a “Libya model” for North Korea in which the Gadhafi government was toppled after it denuclearized, and his more recent abandonment of the Iran nuclear deal and threats of military action against Venezuela.

“These inconsistent and hawkish actions are obstacles for needed confidence building” with North Korea, he said (Representative Khanna is the chief author of a congressional resolution, signed by 20 other House Democrats, calling for an end to the Korean War).

The dismal end to the Trump-Kim talks was a sharp contrast to the mood in Hanoi in the days leading up to the summit. As diplomats and the press gathered, Hanoi was suffocating under a thick blanket of smog. But it was also full of excitement: Street vendors advertised T-shirts bearing Kim and Trump’s faces, thousands of badge-wearing journalists from all over the world roamed the streets, and shiny new signs declared Hanoi “the city for peace.”

For Hanoi residents like Cao Thu Hà, 29, an art director at a marketing agency, the summit was an important moment for Vietnam. “It shows that Vietnam is a place where this thing could happen,” she said. “I take that as a good sign for Vietnam.”

Van Nguyen, 29, a freelance interpreter, had a slightly more cynical point of view. “I think Vietnam is chosen because they are a communist country, because North Korea is communist,” she said. “And they can’t go to China because they’re having a trade war with the US. So, this is a neutral zone.”

Although the summit activities interrupted daily life in Hanoi—blocking off streets, forcing some businesses to close, and slowing traffic to a standstill—it was striking just how much the prospect of peace seemed to excite everyone. That made it all the more disappointing when the summit activities were abruptly cut short and Trump ended up boarding Air Force One for Washington.

During his press conference, however, Trump acknowledged the harmful impact of sanctions on the North Korean people and the provocative nature of the US–South Korean war games, which have been a contentious issue for the North. In the eyes of many Koreans and activists, his willingness to engage with Kim Jong-un and take steps to build trust reflects a dramatic departure from past US approaches and is a hopeful sign for the future.

“This is a moment when the international community must put pressure” on countries that have sided with the United States in this conflict, Christine Ahn, the founder of Women Cross DMZ, told Democracy Now! from Hanoi. “Korea wants peace and the international community has a responsibility to support it.”