It was reported last month that South Korean President Moon Jae-in might join in the talks between Kim and Trump if their summit in Singapore proves successful.
Trump flew into Singapore's Paya Lebar Air Base on Sunday aboard Air Force One. After shaking hands with the Singapore foreign minister, Kim sped through the streets in a limousine, two large North Korean flags fluttering on the hood, surrounded by other black vehicles with tinted windows and bound for the luxurious and closely guarded St. Regis Hotel.
May 16:North Korea abruptly cancels a high-level meeting with the South and threatens to cancel the summit with Trump too in protest over U.S.
The Japanese prime minister will have been encouraged by Trump's insistence - during a joint Rose Garden press conference - that the summit will be only the start of a process and his vow to raise the issue of Japanese abductees in the North.
There are worries from some quarters about Kim's intentions and his willingness to actually follow through on any commitment he might make in Singapore. "They have no way to obtain information about what South Korea or the United States look like".
A USA official says Monday that the leaders will meet for up to two hours before an expanded bilateral meeting with their respective advisers.
Trump acknowledged uncertainty around the highly anticipated summit, saying he was bolstered by discussions in the run-up to the meeting and would not guarantee a specific outcome from the talks.
"The summit will represent a major diplomatic win for Mr. Trump ahead of the USA midterm elections later this year".
But Trump - for whom a major accomplishment would bolster his position ahead of midterm elections in November - baffled observers when he said he did not think he had to prepare "very much" for the summit. On June 1, he said the summit was back on, prompting urgent preparations and a wave of promotions from businesses looking to cash in.
Unlike traditional summits between heads of state, where most of the work is completed in advance, USA officials say the only thing certain ahead of these talks will be their unpredictability. Seeing Nobel Peace Prize laurels and eyeing potential to show up his critics at home and overseas, Trump is granting Kim the global legitimacy he's long sought in hopes of securing a legacy-defining accord.
"We will not be surprised by any scenario", said the official.
But critics have warned that the meeting risks being largely light on substance considering what is believed to be a wide gap between the USA and the North on the denuclearization issue. And Trump is the first US president willing to sit-down with Kim with so few concessions, believing his self-professed negotiating prowess will guide him though uncharted diplomatic waters.
Another guest, challenged by the same North Korean official, said she had taken photos only of the lobby and refused to show her phone.
However, the United States is not expecting to get a final deal in Singapore.
"The picture that emerged from literally dozens of interviews bears a striking similarity with the man he has emerged into today", a source who spoke to Axios said.
When Trump and Kim meet at 9 a.m. (0100 GMT) on Tuesday they will be making history as leaders of their two countries have never met previously - or even spoken on the telephone.