HANOI, Vietnam • President Donald Trump framed the breakdown of his nuclear summit with North Korea’s Kim Jong Un as wisely knowing when “to walk.” But the collapse revealed the limits of his unique brand of personal diplomacy and raised concerns about future efforts to disarm a global threat.

Eyeing the history books and a much-needed political victory, Trump bet big on the two-day Vietnam summit only to be forced to explain away its sudden failure.

The president and North Korea gave conflicting explanations of what went wrong, though the result actually was a relief to some critics and even some Trump supporters who feared he might give too much away in pursuit of a deal.

Trump, the businessman who was elected in part on his boasts of deal-making prowess, said a proposed agreement was “ready to be signed.” But he said he refused to accept what he described as North Korean insistence that all U.S. sanctions be lifted without the North committing to eliminate its nuclear arsenal.

“I’d much rather do it right than do it fast,” the president said. “We’re in position to do something very special.”

The North said it had demanded only partial relief from the punishing sanctions.

Trump had pushed for the summit, telling wary aides that his personal chemistry with North Korea’s young and reclusive leader outweighed any need for detailed, staff-level talks to iron out differences before either head of state set foot in Hanoi.

Secretary of State Mike Pompeo, who along with his special envoy for North Korea, Stephen Biegun, had been leading the preparatory effort, said staff work had achieved some results but that negotiators had intentionally left some of the most contentious issues unresolved.

“We were hoping we could take another big swing when the two leaders got together,” he said as he flew from Vietnam to the Philippines after the summit collapsed.

“We did. We made some progress. But we didn’t get as far as we would have hoped we would have gotten.”

Pompeo noted that “when you are dealing with a country that is of the nature of North Korea, it is often the case that only the most senior leaders have the capacity to make those important decisions.”

Echoing the refrain that “no deal is better than a bad deal” — often used during the Obama administration by critics of its Iran negotiations — there was relief in some quarters that the president had not impulsively agreed to concessions without much in return.

“Kudos to him for walking away from the table,” said Jonathan Schanzer of the Foundation for Defense of Democracies, a Washington think-tank that has been highly skeptical of Trump’s efforts with Kim Jong Un. “No deal is, in fact, better than a bad.”

And White House aides stressed that Trump stood strong. Some observers evoked the 1987 Reykjavík summit between Ronald Reagan and the Soviet Union’s Mikhail Gorbachev, a meeting that ended without a nuclear weapons deal but laid the groundwork for a future agreement.

Longstanding U.S. policy insists that U.S. sanctions on North Korea will not be lifted until that country commits to, if not concludes, a complete, verifiable and irreversible end to its nuclear weapons program.

Trump, who did not consult with allies South Korea and Japan before breaking off the talks, declined to restate that goal Thursday, saying he wanted to retain flexibility with Kim.

Air Force One with President Donald Trump aboard takes off Thursday at Nom Bar International Airport in Hanoi, Vietnam.

the associated press