"Stock Market up almost 40% since the Election, with 7 Trillion Dollars of U.S. value built throughout the economy," the president wrote in a series of pre-dawn tweets sent from Singapore.

"Lowest unemployment rate in many decades, with Black & Hispanic unemployment lowest in History, and Female unemployment lowest in 21 years. Highest confidence ever!"

Trump was due to meet Kim from 9:00 am Tuesday (0100 GMT) for a handshake and hours of meetings that were unthinkable just months ago.

"Meetings between staffs and representatives are going well and quickly....but in the end, that doesn't matter. We will all know soon whether or not a real deal, unlike those of the past, can happen!" he tweeted.

Pointing at the recent release of three American hostages and Pyongyang's pledge to refrain from further nuclear or missile tests, Trump charged that "these pundits, who have called me wrong from the beginning, have nothing else they can say!"

"We will be fine!" he tweeted.

The United States are demanding that North Korea denuclearize in exchange for security guarantees.