Experts on North Korea say that the shortened meeting time leaves nearly no room to forge a path for Pyongyang's "complete, verifiable, irreversible denuclearization", or CVID, which the US State Department was promising just last week. Secretary of State Mike Pompeo said the delegations were "rapidly" making progress, but it will come down to the meeting between the two leaders.
Authorities have beefed up security around the hotels where Trump and Kim (Saint Regis) will be staying in central Singapore.
Rodman said he hopes to surprise his friend Kim with his appearance during the summit.
But it was only Monday morning in North Korea that the government news agency reported that Kim was in Singapore, had met with the prime minister and would meet Trump on Tuesday.
Officials remain uncertain what will come out of Tuesday's unprecedented summit, the first of its kind between a sitting US president and the leader of North Korea.
Lobster bisque, beef tenderloin and ice cream were on the lunch menu, and there was also an early birthday cake for Trump, who turns 72 on Thursday.
The North Korean leader reportedly arrived at Changi Airport in Singapore Sunday afternoon, where he was met by the Minister for Foreign Affairs Vivian Balakrishnan.
AFP 2018 Saul Loeb World Follows Every Step of Historic Trump Kim Summit
"It is our contribution to an worldwide endeavor which is in our profound interest", he told reporters on Sunday.
Trump has said he'll know within minutes whether a deal can be made.
As Trump and Singapore's Prime Minister Lee Hsien Loong sat down for a working lunch at the Istana house, the president sounded optimistic, telling Lee, "We've got a very interesting meeting in particular tomorrow, and I think things can work out very nicely".
Trump has in the past week described the meeting as the first in a process and meant for the two leaders to get to know each other. Her earlier trip to South Korea in January triggered a media frenzy.
Trump advisers cast his actions as a show of strength before the Kim meeting.
Just meeting with Trump will also give Kim a recognition North Korea has long sought, setting him up as global player and the leader of a country worthy of respect.
He said about half of the cost is for security. "North Korea relationship, which can be attributed to their vision".
The rare public appearance of Kim, waving and smiling to onlookers, adds to the more affable image of the young leader that has emerged since his summit in April with South Korean leader Moon Jae-in.More news: Times Trump Helped Putin When He Probably Shouldn't Have Done