Kim's entourage is staying at the St Regis, less than 10 minutes walk away, with a motorcade that features a dozen North Korean bodyguards in dark suits who jog in Singapore's drenching heat beside his armoured vehicle.
Given the uncertainty and the constant back and forth, there has been much speculation the world over about the possible outcomes of the Trump-Kim meeting, especially about whether Pyongyang would agree to complete denuclearisation.
The report also said Mr Kim was accompanied by his foreign minister Ri Yong Ho, defence minister No Kwang Chol and sister Ms Kim Yo Jong.
Singapore's Ministry of Foreign Affairs (MFA) released a statement saying the two discussed mutual relations and the situation on the Korean peninsula, with Prime Minister Lee thanking Kim for his and Trump's "bold and admirable decision" to hold the summit.
President Donald Trump said Monday his historic summit with North Korean leader Kim Jong Un in Singapore could "work out very nicely" as officials from both countries met to narrow differences on how to end a nuclear stand-off on the Korean peninsula. "You would start at least a dialogue, because, you know, as a deal person, I have done very well with deals".
Just hours before what could be the most important meeting of his life, a seemingly relaxed and confident Kim Jong Un took a night on the town in Singapore, taking selfies and being greeted by cheering onlookers.
But Mr Trump warned "he was prepared to walk away" if the summit did not go well.
The United States delegation at tomorrow's expanded bilateral meeting will include Secretary of State Mike Pompeo, Chief of Staff John Kelly, and National Security Advisor John Bolton.
Isolated Kim takes big gamble leaving home for Trump summit
So how should Trump communicate with Kim? The move was in reaction to North Korea's criticism of U.S. vice president Mike Pence's statement that the country could meet the same fate as Libya if it failed to meet a nuclear deal with the US.
At issue is whether Kim would be willing to abandon a nuclear weapons program that has advanced rapidly in recent years, posing an increasing threat to the USA and its allies.
Donald Trump has said that if the Singapore parley is a success, he will invite Kim Jong-un to the White House.
"North Korea best not make any more threats to the United States", said Trump, his arms folded in defensive and bellicose body language. He told reporters he thinks he will know nearly immediately whether a deal can be made, saying: "I will know, just my touch, my feel".
But while Kim has made some gestures in that direction - suspending nuclear and missile tests and making a show of disabling a nuclear test facility - veteran diplomats are skeptical that North Korea will surrender its nuclear weapons altogether.
"No matter what happens, President Trump and Kim Jong Un are going to call it a success", said former Central Intelligence Agency analyst Sue Mi Terry, who's now a senior fellow at the Center for Strategic and International Studies. -North Korea summit in Singapore.
In exchange for North Korea's cooperation, the administration is offering Kim both security guarantees and economic aid.
He has also raised the possibility of further summits and an agreement ending the Korea War by replacing the armistice signed in 1953 with a peace treaty.