SEOUL, South Korea — One of Kim Jong Un's top lieutenants is on his way to the United States to discuss a possible summit between the North Korean leader and President Donald Trump.

But history shows that such trips don't always lead to summits: The high hopes raised by a similar North Korean mission to Washington to set up a leaders' summit 18 years ago ended up dashed.

Kim Yong Chol, a vice chairman of the ruling Workers' Party who was seen in the Beijing airport on Tuesday by The Associated Press, has been deeply involved in the diplomacy that followed Kim Jong Un's sudden outreach to Washington and Seoul earlier this year. Trump later confirmed that Kim Yong Chol was flying to New York.

We have put a great team together for our talks with North Korea. Meetings are currently taking place concerning Summit, and more. Kim Young Chol, the Vice Chairman of North Korea, heading now to New York. Solid response to my letter, thank you! — Donald J. Trump (@realDonaldTrump) May 29, 2018

Kim Yong Chol is among a small group of North Korean officials who have accompanied Kim Jong Un to all four of his summits with foreign leaders in recent months — twice with South Korean President Moon Jae-in and twice with Chinese President Xi Jinping. He also visited South Korea in February to attend the closing ceremony of the Winter Olympics at the start of Kim Jong Un's charm offensive.

Kim Yong Chol, who is about 72, is a contentious figure outside North Korea.

Before taking up the job responsible for relations with South Korea in 2016 he was a four-star army general and a military intelligence chief who is thought to have been behind a slew of provocations, including two deadly attacks in 2010 that killed 50 South Koreans and an alleged 2014 cyberattack on Sony Pictures. Both Seoul and Washington imposed sanctions on him in recent years.

While in the United States, South Korean media reported Kim Yong Chol will likely meet Secretary of State Mike Pompeo, who visited Pyongyang twice recently, to finalize plans for the North Korea-U.S. summit.

Kim Yong Chol. Korea Pool via AFP-Getty Images

His journey follows a recent diplomatic back-and-forth that began when Trump on Thursday abruptly backed away from the meeting, citing hostile comments by the North. Trump then announced the summit could still happen in Singapore on June 12, as initially scheduled, after North Korea issued an unusually conciliatory statement about his cancellation of the summit.

Subsequently, U.S. and North Korean officials on Sunday began preliminary talks at the Korean border to set the agenda for the summit. The countries were expected to hold another set of working-level meetings in Singapore to discuss protocol, security and other logistical issues for the summit.

While Kim Yong Chol's trip to the United States could further brighten the prospects for the summit, history shows that things could still crumble at the last minute even after an exchange of high-level officials.

In October 2000, then North Korean leader Kim Jong Il, the late dictator father of Kim Jong Un, sent Vice Marshal Jo Myong Rok to Washington on a then-unprecedented goodwill mission. Jo, who died in 2010, remains the highest-level North Korean official to visit the United States since the end of the 1950-53 Korean War.

Secretary of State Madeleine Albright is greeted by North Korea's Vice Chairman of National Defense Jo Myong Rok in Pyongyang, North Korea, on Oct. 24, 2000. Chien-Min Chung / AP file

Jo's trip came as the two countries were seeking closer ties following North Korea's first-ever summit talks with South Korea in June 2000.

During his Washington visit, Jo met then President Bill Clinton, conveyed a letter from Kim Jong Il and met Secretary of State Madeleine Albright and Defense Secretary William Cohen. Jo said that improved relations "will be good for both countries and for peace and stability on the Korean Peninsula and the Northeast Asian region as well."

About three weeks later, Albright made a historic reciprocal trip to Pyongyang to try to arrange a North Korea trip by Clinton. Some U.S. critics suspected Clinton was angling for a hasty foreign policy triumph in his last months in office.

During her stay in Pyongyang, Kim Jong Il took Albright to one of the mass games spectacles that included a giant mosaic displaying a rocket flying into the sky. "This will be our last missile," Kim reportedly told Albright at the time, in an apparent reference to a medium-range ballistic missile the North fired over Japan two years earlier, which stunned the region.

The warming ties between the two countries chilled after President George W. Bush took office in January 2001, taking a tough line on the North. The nuclear confrontation deepened in 2002, with the Bush administration accusing North Korea of running a clandestine uranium enrichment program in breach of a 1994 disarmament deal.

Clinton eventually visited North Korea as a former president in 2009 to secure the freedom of two detained American journalists.