TRUMP CANCELLED SUMMIT WITH NORTH KOREA

WASHINGTON — President Trump, citing a flurry of hostile statements from North Korea, pulled out of a highly anticipated summit meeting with Kim Jong-un on Thursday, telling the North Korean leader “this missed opportunity is a truly sad moment in history.”

But Mr. Trump said later that the meeting with Mr. Kim, which had been scheduled for June 12 in Singapore, could still happen, even as he renewed threats of military action against the North and vowed to continue a campaign of economic pressure against Mr. Kim’s regime.

The mixed messages deepened the uncertainty around a diplomatic encounter that had an air of unreality from the time in March when Mr. Trump spontaneously accepted Mr. Kim’s invitation to meet.

The president made his announcement in a formal and at times mournful-sounding letter to Mr. Kim, in which Mr. Trump cited North Korea’s derisive statements about Vice President Mike Pence as the specific reason for canceling the meeting.

“I believe this is a tremendous setback for North Korea and, indeed for the world,” Mr. Trump said at a bill-signing ceremony later in the morning. He said he was waiting to see whether Mr. Kim would take “constructive dialogue and actions” toward relinquishing his nuclear arsenal.

“I think they want to do what’s right,” Mr. Trump said. “I really think that they want to do — and it was only recently that this has been taking place. And I think I understand why it’s been taking place.”

The summit had seemed to be on perilous ground even before the most recent exchanges between Washington and Pyongyang. American and North Korean officials staked out deeply divergent positions on how quickly the North should surrender its nuclear arsenal, casting a shadow on what would be a history-making encounter that clearly beguiled both leaders.

“Based on the tremendous anger and open hostility displayed in your most recent statement, I believe it is inappropriate, at this time, to have this long-planned meeting,” Mr. Trump wrote. “Please let this letter serve to represent that the Singapore summit, for the good of both parties, but to the detriment of the world, will not take place.”

A North Korean official had referred to Mr. Pence as a “political dummy” after the vice president said Mr. Kim could meet the same fate as Libya’s leader, Col. Muammar el-Qaddafi, if he did not make a deal with the United States. Libyan rebels, aided by a NATO bombing campaign, killed Colonel Qaddafi during the Arab Spring upheavals in 2011.

North Korean officials were infuriated last week when Mr. Trump’s national security adviser, John R. Bolton, first floated the voluntary disarmament of Libya in 2003 as a precedent for North Korea.

“We will neither beg the U.S. for dialogue nor take the trouble to persuade them if they do not want to sit together with us,” said Choe Son Hui, a vice foreign minister. She said it was up to Washington whether “the U.S. will meet us at a meeting room or encounter us at nuclear-to-nuclear showdown.”

Mr. Trump’s letter left open the possibility that a meeting could get back on track, though he put the onus to do that entirely on the North. “If you change your mind having to do with this most important summit,” he said to Mr. Kim, “please do not hesitate to call me or write.”

He raised that possibility again later in the morning. “It’s possible that the existing summit could take place, or a summit at some later date,” he said. “Nobody should be anxious. We have to get it right.”

There was almost a jilted tone in Mr. Trump’s message, which captured how deeply invested he was in a summit. As recently as Wednesday, he expressed enthusiasm about meeting Mr. Kim, telling Fox News that he would be open to a phased denuclearization of North Korea, provided its nuclear program was rapidly shut down.

That is a more flexible position that the one sketched out by Mr. Bolton, under which North Korea would surrender its entire nuclear program without any reciprocal incentives from the United States.

For Mr. Trump, who never tires of extolling his dealmaker’s skills, the abrupt cancellation also raises questions about he handled Mr. Kim. After threatening the North with “fire and fury” and ridiculing Mr. Kim as “Little Rocket Man,” Mr. Trump accepted the North Korean leader’s invitation to meet on the spot when South Korean officials conveyed it in March.

Mr. Trump’s decision caught his entire national security team off guard. Some officials said they long believed that there was less than a 50 percent chance that the meeting would actually happen.

But the president dispatched his new secretary of state, Mike Pompeo, to work out the logistics for a meeting with Mr. Kim, and he, too, expressed optimism about the encounter. North Korea offered a series of confidence-building gestures, pledging to halt nuclear and missile tests, and releasing three Korean-Americans imprisoned there.

Mr. Kim also told South Korean officials that he would not object to the continuation of joint American-South Korean military exercises, though in recent days, the North Korean news media began complaining about a joint air exercise, Max Thunder.

On Thursday, a few hours before Mr. Trump sent his letter, North Korea destroyed an underground nuclear test site, having invited foreign journalists to witness the demolition.

Mr. Trump’s reversal creates a major crisis for South Korea’s president, Moon Jae-in, who orchestrated the diplomatic thaw that led to the agreement by Mr. Trump to meet. He visited Washington on Tuesday to reassure Mr. Trump about the coming meeting.

Mr. Moon said the cancellation was “disconcerting and very regrettable,” adding that the current communication between North Korea and the United States does not work to resolve the disputes between the two nations. He urged Mr. Trump and Mr. Kim to talk directly.

“The denuclearization of the Korean Peninsula and building a permanent peace on the peninsula is a task we cannot give up or delay,” Mr. Moon said in a meeting on Thursday with his National Security Council, according to his office.

The decision may also fan tensions between the United States and China. Mr. Trump has said he believes North Korea’s tone changed after Mr. Kim met President Xi Jinping in the coastal Chinese city of Dalian in early May. Mr. Trump suggested that Mr. Xi might be using China’s influence over North Korea as leverage in trade negotiations with the United States.

“I think Xi told Kim to slow down,” said Joseph Y. Yun, who was until recently the State Department’s senior diplomat on North Korea. “Also, I think Kim was getting pushback from his own folks, as Trump was.”

Other experts said the failure was predictable, given the yawning gulf between the two sides.

“It was obvious from the president’s tweets that he had not studied the prior negotiations with North Korea,” said Michael J. Green, a former Asia adviser to President George W. Bush. “If he had spent time with anyone who had done this before, it was clear that North Korea was going for sanctions relief and de facto recognition as a nuclear weapons state.”