WASHINGTON — Summoned to the Oval Office on the spur of the moment, a South Korean envoy found himself face-to-face with President Trump one afternoon last week at what he thought might be a hinge moment in history.
Chung Eui-yong had come to the White House bearing an invitation. But he opened with flattery, which diplomats have discovered is a key to approaching the volatile American leader.
“We could come this far thanks to a great degree to President Trump,’’ Chung said. “We highly appreciate this fact.’’
Then he got to the point: The United States, South Korea, and their allies should not repeat their “past mistakes,’’ but South Korea believed that North Korea’s mercurial leader, Kim Jong Un, was “frank and sincere’’ when he said he wanted to talk with the Americans about giving up his nuclear program.
Kim, he added, had told the South Koreans that if Trump would join him in an unprecedented summit meeting, the two could produce a historic breakthrough.
Trump accepted on the spot, stunning Chung, the other high-level South Koreans who were with him, and the phalanx of US officials who were gathered in the Oval Office.
Those officials thought the president would take more time to discuss such a decision with them first. Defense Secretary Jim Mattis and Lieutenant General H.R. McMaster, the president’s national security adviser, both expressed caution. If you go ahead with this, they told Trump, there will be risks and downsides.
Trump brushed them off. I get it, he said.
On Saturday, Trump said he believes that North Korea will abide by its pledge to suspend missile tests while he prepares for the summit in May, the Associated Press reported. He noted in a Twitter message that North Korea has refrained from such tests since November and said Kim ‘‘has promised not to do so through our meetings.’’
‘‘I believe they will honor that commitment,’’ the president wrote.
Earlier Saturday, Trump tweeted that China was pleased that he was pursuing a diplomatic solution rather than ‘‘going with the ominous alternative,’’ and that Japan is ‘‘very enthusiastic’’ about the plan.
Where others see flashing yellow lights and slow down, Trump speeds up. And just like that, in the course of 45 minutes in the Oval Office, Trump threw aside caution and dispensed with decades of convention to embark on a daring, high-wire diplomatic gambit aimed at resolving one of the world’s most intractable standoffs.
The path to a possible meeting led through a thicket of hostility and feints.
Throughout his first year in office, Trump ratcheted up economic sanctions while rattling his nuclear saber at “Little Rocket Man’’ and threatening to “totally destroy North Korea.’’ Kim could match the president he called “mentally deranged.’’
In a New Year’s Day speech, he said he had “a nuclear button on the desk’’ that could launch missiles capable of reaching the United States. Trump responded with a tweet saying that “I too have a Nuclear Button, but it is a much bigger and more powerful one than his.’’
But South Korea’s president, Moon Jae-in, focused on the other part of Kim’s speech, when he said he would send athletes to the Olympics.
A flurry of negotiations ensued at Panmunjom, the “truce village’’ inside the Korean Demilitarized Zone, that, by the standards of inter-Korean talks, went unusually well.
With the Olympics over, it was time for Moon to make his move. This past week, he sent two trusted aides on a two-day trip to Pyongyang: Chung, his national security adviser, and Suh Hoon, his National Intelligence Service director.
Black limousines took the South Koreans to Azalea Hall in the ruling Workers’ Party headquarters, Kim’s workplace. They found Kim and his sister waiting to greet them with broad smiles.
Chung and Suh were the first South Koreans to set foot inside the party headquarters since the Korean War.
Chung had barely launched into his talking points when Kim said “I know’’ and “I understand you.’’ Then he laid out his proposal: talks with the United States on denuclearizing his country; a suspension of nuclear and missile tests during the talks; and his understanding that the United States and South Korea must proceed with annual joint military exercises.
Kim’s invitation was not a surprise to Trump’s team. A US official said they had learned about it from intelligence agencies Thursday morning, so before the arrival of the South Koreans, Trump talked with Secretary of State Rex Tillerson, who was traveling in Africa, about the prospect.
What he did not tell Tillerson was that he was going to accept the invitation.
