US and North Korean officials held preliminary talks at the Korean border and were expected to hold a separate set of working-level meetings in Singapore to discuss protocol, security and other logistical issues for the summit.
Kim Yong-chol accompanied Kim Jong-un at all of his recent meetings with both Chinese President Xi Jinping and South Korean President Moon Jae-in, according to North Korean state-media reports.
On Thursday last Donald Trump cancelled the first-ever meeting between USA and North Korean leaders only to change his mind a day later. "The Secretary will be heading up to NY tomorrow and I believe returning sometime on Thursday".
"Solid response to my letter, thank you!" tweeted Trump.
Kim Yong Chol is a former military intelligence chief and now a vice chairman of the North Korean ruling party's central committee tasked with inter-Korean relations.
FILE - In this May 9, 2018, file photo provided by the North Korean government, U.S. Secretary of State Mike Pompeo, left, shakes hands with North Korean leader Kim Jong Un during a meeting at Workers' Party of Korea headquarters in Pyongyang, North Korea.
A team of US officials led by former USA nuclear negotiator Sung Kim began talks with North Korean officials at the Korean border village of Panmunjom on Sunday to set the agenda for the summit.
"It's moving along very nicely", Trump said at the White House on Saturday.
Led by Sung Kim, a longtime US State Department Korea expert, the preparatory talks are expected to last until Thursday in Panmunjom, the "truce village" on the border.
His trip comes after Mr Trump pulled out of the planned summit for Singapore on June 12, prompting frenzied talks to salvage the historic occasion.More news: Visa debit cards not working in European-wide outage
More news: Trump Speaks With Abe About Coordination On Korea Summit Preparations
More news: Trump hits Canada, Mexico, EU with steel and aluminum tariffs
Kim Yong Chol, previously chief of the Reconnaissance General Bureau, a top North Korean military intelligence agency, coordinated the North Korean president's two meetings with U.S. Secretary of State Mike Pompeo in April and May.
With much of the information about ongoing discussions at Panmunjeom withheld, what the countries are still working out appears to be the first steps they would take on the path to denuclearization - how much North Korea proactively dismantles its nuclear weapons programs, and how much rewards the United States can grant to the North in return, they say. -North Korea working-level meeting was set to take place in Singapore. It defends its nuclear and missile programs as a deterrent against what it sees as USA aggression. The United States has been pushing for "complete, verifiable and irreversible dismantlement" - a high bar that would require North Korea to relinquish its entire nuclear program and allow verification by worldwide inspectors.
The potential summit was thrown in doubt last week when President Trump abruptly canceled the event; saying Kim's "outright hostility" prompted his administration to withdraw from the meeting.
North Korea's flurry of diplomatic activity following a torrid run in nuclear weapons and missile tests in 2017 suggests that Kim Jong Un is eager for sanctions relief to build his economy and the global legitimacy the summit with Trump would provide.
Trump's confirmation of the arrival of the U.S. team in Pyongyang comes hours after The Washington Post reported the diplomatic mission, reports Efe news.
There are speculations that the top North Korean official may pay a visit to Trump as a special envoy from Kim Jong-un or convey a letter during the NY trip.
White House also said on Tuesday that Trump would meet with Japanese Prime Minister Shinzo Abe in Washington on June 7. Secretary of State Mike Pompeo will head over to NY on Wednesday to meet him.
He is widely believed to have masterminded the attack on a South Korean naval corvette, the Cheonan, in 2010, leading to the deaths of 46 sailors.
United States and South Korean officials haven't confirmed the details of the pre-summit negotiations between Washington and Pyongyang at the border.
"Therefore, 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".