Tuesday, May 22, was a big day for the Koreas in Washington. Moon Jae-in, South Korea’s famous peace-making president, was in town, meeting one-on-one with President Trump on a rescue mission to save his June 12 summit with Kim Jong-un and keep Moon’s dream alive for a historic peace settlement in Korea. Later, Moon was the guest of honor at a ceremony marking 136 years of US-Korean friendship.

But his mission failed, and now that relationship is being tested like never before.

On Thursday morning, May 24, The Washington Post reported breaking news from the White House: “Trump cancels summit with North Korean leader Kim Jong Un.”

In a letter to Kim filled with mixed messages of concern and confrontation, Trump said the summit with North Korea, scheduled for June 12 in Singapore, was off.

“Sadly, based on the tremendous anger and open hostility displayed” in recent statements from Pyongyang, “I feel it is inappropriate, at this time, to have this long-planned meeting,” Trump wrote. What set him off was a blistering polemic published Wednesday night by Choe Son-hui, a North Korean vice foreign minister well-known to US officials and negotiators.

Choe, who is reportedly close to Kim Jong-un, criticized Vice President Mike Pence for his recent warning on Fox News that North Korea could end up like Libya—a state broken by a US-led regime-change operation—if it fails to cut a deal with Trump ending its nuclear-weapons program.

“As a person involved in the U.S. affairs, I cannot suppress my surprise at such ignorant and stupid remarks gushing out from the mouth of the U.S. vice-president,” Choe wrote. “Whether the U.S. will meet us at a meeting room or encounter us at nuclear-to-nuclear showdown is entirely dependent upon the decision and behavior of the United States.” It was the third statement from North Korea in a week threatening to cancel the talks.

It’s not hard to understand why Choe would take umbrage at Pence. The US vice president is widely detested in Korea for his rude and grouchy behavior toward the North Korean delegation during the Winter Olympics earlier this year in PyeongChang, where Moon’s diplomacy with Kim got off the ground. Moreover, even as the summit was being planned, Pence was citing John Bolton, Trump’s controversial national-security adviser, on Libya and the necessity of a military option against the North if negotiations fail to end its nuclear program.

But Choe’s statement was shocking in part because she has been one of the chief interlocutors with former US officials and negotiating experts who meet every few months with North Korean diplomats in the informal talks known as Track Two negotiations. American officials were also “pointing to the ‘showdown’ part” of her remarks as a cause of concern, Olivier Knox, who covers the White House as chief Washington correspondent for SiriusXM, told The Nation via Twitter (“take with a grain of salt,” he added).

Suzanne DiMaggio, a director and senior fellow at New America who specializes in complex negotiations and has met with Choe several times, said she wasn’t surprised. “Trump’s letter points to the ‘open hostility’ in Choe’s statement as the reason for canceling,” she told The Nation in an e-mail. “But a harsh reaction was to be expected given Bolton’s insistence on following a ‘Libya model’—a not-so-subtle nod to regime change. Showing weakness isn’t an option for North Korean negotiators. An old hand like Bolton knows this playbook well.”

Ironically, Trump’s cancellation was announced just hours after North Korea confirmed the dismantlement of the nuclear test site at Punggye-ri in the country’s mountainous northeast. Several dozen reporters from China, Russia, Britain, South Korea, and the United States (including CNN’s Will Ripley and CBS’s Ben Tracy) were invited to observe the action. It was one of the first tangible North Korean steps for meeting US and South Korean demands that it end its nuclear program.

But with the release of Trump’s letter, the days of confrontation suddenly seemed to be back. Speaking on live television an hour after the news broke, Trump said the US military “is ready if necessary” to respond to any “foolish or reckless” act by the North. And in Seoul, where it was past midnight, President Moon called in his security advisers for an emergency meeting, expressed “deep regret” about the cancellation, and said the denuclearization of North Korea should not be delayed, according to Yonhap News.

The fast-moving events came after weeks of increasing tensions between North Korea, South Korea, and the United States over the peace process.

A week ago, angered again by US-South Korean military exercises and offended by US demands for immediate denuclearization without reciprocal steps from Washington, the North canceled high-level meetings with the South and threatened to boycott the summit with Trump. Its strongest language came from Kim Kye Gwan, a senior North Korean negotiator also well known to US diplomats.

Specifically, Kim ripped into Bolton for suggesting the Libya-style denuclearization process, which, as DiMaggio notes, North Korea basically sees as regime change on steroids. The Bolton plan, he said, would “impose” on North Korea “the destiny of Libya or Iraq,” and is therefore a nonstarter. Kim also blasted the administration for saying that North Korea would trade away its nuclear program simply for economic aid and forswear any political concessions.

Kim’s critique stunned the White House and the US media, which immediately began to speculate that the US-North Korean negotiations over its denuclearization were in jeopardy. As Moon and Trump sat down on Tuesday at the White House, the initial news was that the summit may be delayed. “There’s a very substantial chance that it won’t work out,” Trump told reporters in the Oval Office, adding his usual “We’ll see.”

But as the Korean side of the story emerged, it appeared that Moon might have persuaded Trump otherwise.

Moon told Trump that there was no need for doubt over the North’s willingness to attend the summit, according to a transcript published by his ministry of foreign affairs. The report acknowledged the need for “concrete negotiations” to “achieve denuclearization and the stability of the [Kim] regime,” and Moon predicted that Trump “will be able to bring an end to the Korean War that has lasted over the past 65 years.” The headline in Yonhap News, the government-owned wire service, was “Moon keeps U.S.-N. Korea summit from falling apart, for now.”

To get there, Trump reportedly agreed to a more flexible phased dismantling of North Korea’s arsenal more aligned with Moon’s step-by-step approach. “It would certainly be better if it were all in one,” Trump said in remarks analyzed in The New York Times by a raft of unhappy North Korea experts from the Center for Strategic and International Studies and the Brookings Institution. “Does it have to be? I don’t think I want to totally commit myself.”

Still, the South Koreans were sanguine, and on Tuesday were vowing to get the Singapore meeting back on track. Chung Eui-yong, Moon’s national security adviser and the man running his North Korea initiative, told the Korean president’s press pool that “there is a 99.9 percent chance” the US–North Korea summit would be held as scheduled.

In the White House meeting, Trump blamed China—and not the North—for the problems that have come up, saying that Kim’s views on denuclearization may have hardened after he visited Chinese President Xi Jinping for the second time a few weeks ago. “There was a different attitude by the North Korean folks after that meeting,” he mused. “I can’t say that I’m happy about it.”

But even experts wary of Kim’s pronouncements said that Pyongyang’s outburst was due to Trump’s and Bolton’s mishandling of the negotiations (earlier in the week, Trump had ruled that Libya was the wrong approach, noting that the country had been “decimated” by US and NATO forces after it denuclearized—effectively throwing Bolton under the bus).

After hearing Trump’s criticism of China, Jeffrey Lewis of the Middlebury Institute of International Studies, who has in the past raised doubts about Moon’s guarantees to Trump on North Korea, responded: “North Korea’s position has not changed. This is not China’s fault. It’s not Kim’s fault. It is Trump’s fault.” In an opinion piece for The Washington Post, he noted Kim Kye Gwan’s bitter denunciation of Bolton: “we do not hide our feeling of repugnance towards him.”

Many in South Korea seem to agree. In an extraordinary article from Seoul on May 21, the Post’s Anna Fifield quoted a string of South Korean officials and analysts blasting Bolton as the sole cause for “the sudden problems in the diplomatic process.”

One official close to President Moon, speaking anonymously, said Bolton’s martial approach endangered both North and South. “He seems to think the U.S. can fight another war on the Korean Peninsula, so from our perspective, as the people living on the Korean Peninsula, he is very dangerous,” the official said.

But South Korea could share in the blame as well. At the Panmunjom summit on April 27, the Koreas agreed to establish a peace process that would lead to a treaty formally ending the Korean War, and to begin the arduous task of de-escalating their decades old military confrontation.

In preliminary talks, as a way to kick-start the process, Kim had dropped his opposition to “normal” war exercises between the United States and South Korea, meaning he would accept the drills as long as they didn’t include “strategic” weapons, such as B-52 bombers and nuclear-armed aircraft carriers. Their presence in Korea is viewed by Kim as both provocative and threatening.

But on May 16, a few days into the planned “Max Thunder” air exercises in South Korea, North Korea’s news service, the KCNA, ripped into the exercises, pointing out that the United States planned to deploy B-52s stationed in Guam and advanced F-22 attack fighters based in Japan. The Max Thunder drill “is an undisguised challenge to the Panmunjom Declaration and a deliberate military provocation to the trend of the favorably developing situation on the Korean Peninsula,” the editorial said. The KCNA report, released after North Korea canceled a meeting with the South and threatened to boycott the summit with Trump, added, “We will closely watch the ensuing behavior of the US and the south Korean authorities.”

The criticism apparently led to the unusual sight of the Pentagon backing down. On May 18, the US Pacific Command announced that it was scrapping plans for the B-52s (which are configured to carry nuclear weapons) to participate in the air drills, which were originally designed to include Japanese aircraft.

Later, the South Korean defense ministry confirmed the decision, saying “the Max Thunder exercise is carried out to train fighter pilots. Hence, the B-52s are not included.”

After President Moon returned to Seoul on Thursday, his aides suggested that his rescue efforts may have won the day, and that the summit and the peace process might be back on. They also let it be known that its own disputes with the North had been resolved as well. At the end of Moon’s visit, his chief spokesman, Yoon Young-chan, said that the high-level talks between North and South would likely resume after May 25, when the joint military drills are completed.

One reason for Moon’s optimism was the reopening of the important back channel between South Korea’s National Intelligence Service and its counterpart, the North’s United Front Department.

According to Hankyoreh, after Pyongyang initially refused to allow South Korean reporters to witness the dismantlement of its nuclear test site, the two intelligence services “reportedly went to work frantically behind the scenes.” (Until the recent breakdown, ties among the CIA and North and South Korean intelligence have been an important conduit for the three countries.)

The events on Thursday lent an air of poignancy to the ceremony the South Korean president attended on Tuesday. Just a mile north of the White House, in Northwest Washington, the South Korean embassy threw a party, complete with traditional Korean drumming and dancing, to celebrate the restoration of a venerable house that was once the site of Korea’s first diplomatic mission to the United States, which lasted from 1889 to 1905.

The Old Korean Legation, as they now call it, has a sad, tangled history: It was temporarily lost when Japan colonized Korea in 1910 and “forcibly bought” the building before selling it to an American buyer. Tuesday marked its reopening as a Korean national property after its repurchase in 2012.

“Today on this historic site, we raise the Korean flag once again,” said Cheon Joonho, the embassy’s minister for public communications, who was standing in for ambassador Cho Yoon-je. “About 100 years ago, Korean diplomats watched the loss of their country’s sovereignty with an aching heart. If they were here with us today, they must feel very proud that the country they loved has achieved unprecedented economic success with full-fledged democracy.”

Just as in the past, he added, “the situation surrounding the Korean peninsula today is very critical. As we reflect the history of the Old Korean Legation, we can also have hope to attain permanent peace and prosperity of the Korean peninsula, overcoming the present history of division.” Later in the day, after his meetings at the White House, President Moon dropped by the Legation house with South Korea’s First Lady, Kim Jung-sook.

In their own ways, the two events—the summit at the White House and the ceremony at the legation—underscored the complexity of the ties between Korea and the United States, which date back to their first treaty of “Peace, Amity, Commerce and Navigation” in 1882. But that relationship is often complicated by a mutual history—including entanglements with China, Japan, and North Korea—that is often interpreted differently in Seoul and Washington. That can lead to misunderstandings, just as they have in the current crisis.

But it’s not too late for Trump and Moon to get negotiations back on track, said DiMaggio.

“In order to salvage this process, the Trump administration should step back from all of the contradictory public messaging, including the poorly veiled references to regime change, and speak in one voice that is firmly in support of diplomacy,” she said. “Time isn’t on our side, as the North Koreans have played their hand with Seoul and Beijing well, already eroding Trump’s maximum pressure campaign.”