A senior North Korean official has arrived in New York in the highest-level official visit to the United States in 18 years, as Donald Trump and Kim Jong-un sought to salvage prospects for a high-stakes nuclear summit.

Kim Yong-chol, the former military intelligence chief and one of the North Korean leader’s closest aides, landed mid-afternoon on an Air China flight from Beijing. Associated Press journalists saw the plane taxi down the tarmac before the North’s delegation disembarked at JFK international airport.

During his unusual visit, Kim Yong-chol was to have dinner Wednesday with Mike Pompeo, the secretary of state who traveled from Washington to see him. The two planned a “day full of meetings” on Thursday, the White House said. Their talks will be aimed at determining whether a meeting between Trump and Kim Jong-un, originally scheduled for 12 June but later canceled by Trump, can be restored, US officials have said.

The talks come as preparations for the highly anticipated summit in Singapore were barreling forward on both sides of the Pacific Ocean, despite lingering uncertainty about whether it will really occur, and when. As Kim and Pompeo were meeting in New York, other US teams were meeting with North Korean officials in Singapore and in the heavily fortified Korean Demilitarized Zone.

“If it happens, we’ll certainly be ready,” White House spokeswoman Sarah Huckabee Sanders said of the Singapore summit. Regarding the date for the meeting, she added: “We’re going to continue to shoot for June 12th.”

North Korea’s flurry of diplomatic activity following nuclear weapons and missile tests in 2017 suggests that Kim is eager for sanctions relief to build his economy and the international legitimacy the summit with Trump would provide. But there are lingering doubts on whether Kim will ever fully relinquish his nuclear arsenal, which he may see as his only guarantee of survival.

Trump announced that Kim Yong-chol was coming to New York for talks with Pompeo in a tweet on Tuesday, in which he said he had a “great team” working on the summit. That was a shift from last week, when Trump announced in an open letter to Kim Jong-un that he had decided to “terminate” the summit following a provocative statement from the North.

Pompeo, Trump’s former CIA chief, has traveled to Pyongyang twice in recent weeks for meetings with Kim Jong-un, and has said there is a “shared understanding” between the two sides about what they hope to achieve in talks. South Korean media speculated that Pompeo could make a third trip to Pyongyang and that Kim Yong-chol was carrying a personal letter from Kim Jong-un and might push to travel to Washington to meet with Trump.

North Korea’s mission to the United Nations in New York is its sole diplomatic presence in the United States. That suggests Kim might have chosen to first go to New York because it would make it easier for him to communicate with officials in Pyongyang, North Korea’s capital. North Korea and the United States are still technically at war and have no diplomatic ties because the 1950-53 Korean War ended with an armistice, not a peace treaty.

Trump views a summit as a legacy-defining opportunity to make the nuclear deal that has evaded others, but he pledged to walk away from the meeting if he believed the North wasn’t serious about discussing dismantling its nuclear program.

After the North’s combative statements, there was debate inside the Trump administration about whether it marked a real turn to belligerence or a feint to see how far Kim could push the US in the lead-up to the talks. Trump’s letter, the aides said, was designed to pressure the North on the international stage for appearing to have cold feet.

White House officials maintain that Trump was hopeful the North was merely negotiating but that he was prepared for the letter to mark the end of the two-month flirtation. Instead, the officials said, it brought both sides to the table with increasing seriousness.

The White House emphasized that it has remained in close contact with South Korean and Japanese officials as preparations for the talks continue. Spokeswoman Sarah Sanders said Trump will host Japan’s prime minister, Shinzo Abe, on 7 June to coordinate their thinking ahead of the summit. Trump hosted South Korea’s president Moon Jae-in last week.