BEIJING -- At the Truce Village that separates the two Koreas, American diplomats have taken the rare step of crossing the border to meet with their North Korean counterparts. The U.S. delegation is led by veteran diplomat Sung Kim.

He's trying to find out if Kim Jong Un is really willing to give up his nuclear weapons. At the same time, the man who is basically the North Korean leader's chief of staff was spotted in the Beijing airport Monday en route to Singapore, the site of the potential summit.

This weekend President Trump seemed to reverse himself, saying plans for the summit were still moving forward. He then praised North Korea in a tweet, saying:

Our United States team has arrived in North Korea to make arrangements for the Summit between Kim Jong Un and myself. I truly believe North Korea has brilliant potential and will be a great economic and financial Nation one day. Kim Jong Un agrees with me on this. It will happen! — Donald J. Trump (@realDonaldTrump) May 27, 2018

What did happen was a surprise summit between the leaders of North and South Korea on Saturday, and it began with a vigorous bear hug in front of the cameras. Kim and South Korean President Moon Jae-in met for two hours on the North Korean side of the demilitarized zone.

North Korean state media says that at the meeting Kim "expressed his fixed will" that the summit with Mr. Trump take place. The outcome of a summit between two world leaders is usually negotiated before they ever sit down at a table. That often takes months if not years of work and planning.

Mr. Trump's team is now trying to accomplish that in the next 15 days.