President's Trump team, including Secretary of State Mike Pompeo, Chief of Staff John F. Kelly and National Security Adviser John R. Bolton, will join an expanded meeting.
Here is a rundown of the biggest actions that took place overnight, as Singapore is 12 hours ahead of Eastern Daylight Time.
The two are due to meet on Tuesday on the resort island of Sentosa for their high-stakes summit, the first-ever talks between a USA and North Korean leader and the culmination of a head-spinning diplomatic dance.
President Trump has said he will use the summit, scheduled to begin Tuesday, to push for North Korea's denuclearization.
U.S. President Donald Trump holds a summit with North Korean leader Kim Jong Un in Singapore on Tuesday with their talks expected to center on ending the North's nuclear weapons and missile programs in return for diplomatic and economic incentives.
Trump himself seemed optimistic as well.
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Although gaps remain over what denuclearisation would entail, Mr Trump sounded a positive note at the lunch meeting, telling Mr Lee, "we've got a very interesting meeting in particular tomorrow, and I think things can work out very nicely". "But we appreciate your hospitality and professionalism and your friendship".
Meanwhile, diplomats from the USA and North Korea met behind closed doors at The Ritz-Carlton hotel, in a bid to narrow their differences ahead of the Trump-Kim summit tomorrow.
The first came early in the day, showing a glimpse of his morning briefing with Ambassador Sung Kim, the South Korean-born American diplomat who is the U.S. Ambassador to the Philippines.
The fighting ended on July 27, 1953, but the war technically continues today because instead of a difficult-to-negotiate peace treaty, military officers for the US -led United Nations, North Korea and China signed an armistice that halted the fighting.
The North Korean autocrat's every move will be followed by 3,000 journalists who have converged on Singapore, and by gawkers around the world, up until he shakes hands with Mr. Trump on Tuesday.
Trump, 71, landed at Paya Lebar Airbase on board Air Force One after cutting short his time at the G7 summit in Canada. The meeting was briefly canceled by Trump.
The summit - the first ever between a sitting United States president and North Korea's leader - was to kick off at 9 a.m., the White House said.More news: Elon Musk's Boring Company Releases Its 'Not-A-Flamethrower'
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