WASHINGTON -- On his way to Nashville, President Trump ignored questions about the quickly changing status of his summit with North Korean leader Kim Jong Un. But this morning he tweeted: "We have put a great team together for our talks with North Korea."

That echoed what he said over the weekend, saying "we're moving along nicely."

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

The optimism is a complete reversal from just five days ago, when he sent a letter canceling the meeting, and threatened military might if provoked. So what changed?

"Since the president's May 24 letter to North Korean leader Kim Jong Un, the North Koreans have been engaging with the United States," said Heather Nauert, U.S. State Department spokeswoman.

The original meeting date is exactly two weeks away, and officials are linking up across the world to work out details in case it happens.

On Tuesday, Kim Jong Un's right hand man, Kim Yong Chol, arrived in Beijing en route to New York City for meetings with Secretary of State Mike Pompeo. The vice chairman will be the most senior North Korean official to visit the U.S. for diplomatic talks in 18 years.

In Korea's demilitarized zone, a U.S. delegation is meeting with North Koreans to work on summit preparations, and a separate American team is in Singapore coordinating logistics. Next Thursday, President Trump is scheduled to host Japanese Prime Minister Shinzo Abe in Washington to talk about what the White House is calling "the expected summit" with Kim.