The secretary also appeared optimistic about the summit, telling Kim at a lunch in Pyongyang that he was "hopeful that we can work together to resolve this conflict, take away threats to the world and make your country have all the opportunities your people so richly deserve".
Shortly before 3am, the president and first lady boarded the medical plane on which the men had travelled and spent several minutes meeting with them privately. He was detained May 7, 2017, while teaching at Pyongyang University of Science and Technology. "Sending these three Americans home before any concessions have been offered I think is a testament to the president's policy of peace through strength - strong, clear, American leadership with our allies at the table has brought us this far, and we hope it opens the way to a lasting peace". They later gave the president a round of applause.
The former prisoners arrived at Joint Base Andrews near Washington early in the morning.
In a statement Wednesday, South Korean government spokesman Yoon Young-chan called again for Kim Jong Un to release the six South Koreans still held by the North.
Located at the southern tip of Malaysia, Singapore is a regional hub in Southeast Asia whose free enterprise philosophy welcomes trading partners from everywhere.
However, Pyongyang suddenly softened its tone, leading to a flurry of diplomacy, rare talks with South Korea last month and a planned Kim-Trump summit.
On Tuesday, Kim and President Xi had met in a northern Chinese port city.
US officials had looked at several sites other than Singapore for the historic meeting but each was seen as problematic.
The group then emerged at the top of the plane's steps, where the men held up their arms in an exuberant display.
But U.S. and Chinese efforts, coupled with global sanctions, appear to have turned the tide.
CNN reported Wednesday Trump administration officials were moving forward with plans for the meeting to take place in Singapore.
The White House declined to comment on the summit's location.
"We are starting off on a new footing - I really think we have a very good chance of doing something very meaningful".
There will be "no way" to do this without relying on the experts in the government and at the State Department, believes Bell.
White House Press Secretary Sarah Huckabee Sanders told reporters on Wednesday afternoon that "the maximum pressure campaign has worked", adding that in addition to the president's efforts "some of that success is due to our allies and partners", especially the leaders of China, Japan and South Korea. The trio, along with medical personnel, including a psychiatrist, were cloistered in the middle of Pompeo's plane in a small section of 12 business class-size seats that was cordoned off by curtains on both ends.
Mr Trump said he will not disclose whether he will have any personal conversations with Mr Kim as they prepare for their historic summit in the coming weeks. They noted that North Korea has failed to honor previous agreements.
"A lot of very good things have happened", Trump said as he greeted the former prisoners at Joint Base Andrews early Thursday morning.