American student Otto Warmbier is escorted at the Supreme Court in Pyongyang, North Korea, on March 16, 2016. He was medically evacuated from the country on June 13, 2017. (Jon Chol Jin/AP)

Not long after President Trump declared last month that he would be “honored” to meet North Korean dictator Kim Jong Un amid mounting nuclear tensions, a secret encounter took place in Oslo between officials from the two countries.

Joseph Yun, the U.S. special representative to North Korea, had persuaded his boss, Secretary of State Rex Tillerson, to bless the rare, face-to-face dialogue with senior North Korean Foreign Ministry officials after assuring him that the agenda would focus on the status of four American citizens imprisoned by the Kim regime, according to people familiar with the process.

Yun scored a breakthrough when the North Korean delegation agreed to allow Swedish diplomats in Pyongyang, who handle U.S. affairs there, to visit the American prisoners, including 22-year-old University of Virginia student Otto Warmbier.

Ultimately, North Korea allowed only one visit, with a different American held prisoner. As the administration continued to push, Pyongyang urgently requested to see Yun at the United Nations in New York. A June 6 meeting led a week later to Warmbier’s sudden release Tuesday after 17 months of captivity. He was medically evacuated in a coma; the other three Americans remain in captivity.

Whether the back-channel diplomacy will lead to broader talks with North Korea may depend on Warmbier’s condition, and White House officials declined to comment on the geopolitical implications of his case.

(Anna Fifield/The Washington Post)

But the first high-level encounters between the two governments could be significant, at a moment when the countries have been trading threats and readying military forces for a possible confrontation.

Even as North Korea has been escalating its ballistic missile launches and warning of a new nuclear test, Kim continued the “Track 2” dialogue in which former U.S. officials and nuclear experts meet regularly with North Korean counterparts. The dialogue has been regularly scheduled, but not official — until Oslo.

North Korea sent high-level Foreign Ministry officials to Oslo specifically to meet with Yun.

A State Department spokeswoman suggested that it was too soon to predict a deepening of engagement with Pyongyang.

“This is all so fresh,” the spokeswoman, Heather Nauert, told reporters in Washington. “We were just able to get the release of Mr. Warmbier. We are grateful and thankful for that. He is on his way home. I think it’s just too soon to say what that dialogue is going to look like.”

U.S. diplomats, members of Congress and North Korea experts also were hesitant to declare a new chapter in bilateral relations. Several suggested that Kim’s calculus was based less on a bid to continue dialogue with the Trump administration than on a fear that all avenues of engagement would be shut down if Warmbier were to die in North Korea.

“For all of Kim Jong Un’s bravado and his flaunting of the threat of nuclear-armed missiles, he really, really does not want an American citizen to perish under his custody,” said Danny Russel, a State Department official on sabbatical who served as senior Asia director at the National Security Council in the Obama administration.

But Russel acknowledged that a secondary intent of Warmbier’s release “could be a form of diplomatic signaling, the functional equivalent to a lady dropping her handkerchief to see if the gentleman picks it up. . . . Does this go anywhere?”

A congressional aide familiar with the process said Tillerson was adamant that Yun participate in the meetings only under the precondition that the detained Americans be the focus of the agenda and that a pathway was laid out for their release.

“It was not for broader diplomacy or engagement,” said the aide, who, like others, spoke on the condition of anonymity to discuss private deliberations.

But the aide added: “You now have a channel with a senior administration official and a North Korean official with some degree of confidence. I wouldn’t use the word trust, but confidence. Does this lead to anything bigger? Not necessarily. But this sort of engagement is a necessary precondition to have serious discussions.”

Direct, formal talks between Washington and Pyongyang have been on ice since North Korea dropped a proposal in early 2016 to engage in formal peace talks with the Obama administration to officially end the Korean War. The breakdown occurred when Pyongyang refused to include its nuclear program on the agenda.

After North Korea accelerated its nuclear and ballistic-missile testing programs in recent months, the Trump administration declared an end to the Obama-era policy of “strategic patience,” which had aimed to force Pyongyang to freeze its nuclear program through economic sanctions and diplomatic isolation.

A senior administration official declared in April: “The clock has now run out, and all options are on the table for us.”

The administration sent a Navy aircraft carrier strike group toward the Korean Peninsula in May as a warning after Kim tested a ballistic missile in late April that failed shortly after launch. Trump has lobbied China to exert more economic and political pressure on North Korea and has called on leaders of other Asian nations to cut their diplomatic ties with Pyongyang.

But it is unclear how the administration’s strategy of “maximum pressure and engagement” will differ substantially from the policies in place when Barack Obama was president.

In interviews with news outlets in early May, Trump said he would be “honored” to meet with Kim under the right circumstances, and he called the North Korean leader a “pretty smart cookie,” citing his ability to consolidate power in his mid-20s after his father, Kim Jong Il, died in 2011.

In a private conversation with Philippines President Rodrigo Duterte around the same time, however, Trump referred to the younger Kim as a “madman with nuclear weapons.”

Trump’s floating of a potential meeting is radical: No U.S. president has met with a North Korean leader since that nation’s founding in 1948.

“I don’t think this administration is ideologically opposed to talking with North Korea,” said Victor Cha, a Korea expert at the Center for Strategic and International Studies who served as senior director for Asia on the National Security Council in the George W. Bush administration.

But Cha emphasized that the political fallout in Washington over Warmbier’s case could reflect negatively on Pyongyang because of the student’s dire health.

“I have a feeling this will not be seen positively but will be seen negatively,” Cha said. “For medical reasons, they had to get him out. Overall, it might have been meant to spur diplomacy, but I don’t know if that will be the case because of his poor condition.”

According to administration officials, concerns rose when the North Koreans reneged on the Oslo agreement to allow Swedish diplomats to visit all four Americans held prisoner, and then followed through with only one. Then came the sudden request for the diplomatic meeting in New York, where Yun was informed of Warmbier’s deteriorating health.

Trump, after speaking with Tillerson, directed that a plane carrying Yun and medical personnel be sent to Pyongyang, telling — not asking — the North Koreans that it was going to land and that Warmbier must be seen, a senior administration official said.

The visit to his bedside was the first time the United States was able to confirm his status since he was sentenced.