At 6:30 p.m. local time, the two leaders will have a meet-and-greet at the Sofitel Legend Metropole Hanoi hotel, according to the White House.
Trump made no comment to reporters on his aircraft, but had previously tweeted his hopes for a "very productive" meeting, reiterating that North Korea could enjoy economic riches if it gave up its nuclear weapons. Other agreements could be to open liaison offices in each other's countries and adopting denuclearization measures, such as allowing inspectors to observe the dismantlement of North Korea's Yongbyon nuclear reactor, in exchange for a loosening of USA economic sanctions against Pyongyang.
Vietnamese women, wearing traditional long dress "ao dai", wave Vietnamese and U.S. flags while a limousine transporting U.S. President Donald Trump enters Government Office in Hanoi, Vietnam, February 27, 2019.
"Now that we're meeting here again like this, I'm confident that there will be an excellent outcome that everyone welcomes, and I'll do my best to make it happen", Kim said.
A press conference is also scheduled before Trump returns to Washington.
But the president has been dogged by scandal at home, where his former lawyer Michael Cohen described him as a "conman" in nationally televised testimony to Congress starting shortly after Trump finished Wednesday's negotiations on the other side of the world.
"North Korea would be the same, and very quickly, if it would denuclearise".
Mr Trump has been carefully lowering expectations and is no longer pushing for progress on the supposed goal of the talks - North Korean denuclearisation.
Mr Kim could agree to allow a U.S. diplomatic liaison office in Pyongyang, a United States goal dating back to Bill Clinton's administration.
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At the same time, Washington faces mounting pressure to extract significant concessions from Kim, who has so far shown little desire to ditch his nuclear capability.
The two sides haven't even agreed on the meaning of denuclearisation or the ultimate objective of the talks.
Daniel Russel, the top USA diplomat for Asia until 2017, said: "A peace treaty that leaves in place the arsenal of North Korean chemical, biological, and nuclear weapons that directly threaten Americans and our allies is not much of a peace treaty".
"Vietnam is thriving like few places on earth".
While she spoke of the greatness of Kim Jong Un, the other passengers cleverly kept their heads down.
And Trump has invested himself personally in the relationship with Kim, creating the diplomatic equivalent of a Hollywood odd-couple bromance.
Relations between the two mercurial leaders have undergone a dramatic turnaround, from flinging personal insults and threats of destruction to Trump declaring he had fallen "in love" with Kim through an exchange of letters. I just don't want testing.
Arms control expert Jeffrey Lewis said he is not merely concerned about Trump unwisely giving Kim concessions ― he is convinced it will happen.
Critics warn Trump is so keen to score a deal that he could give away too much, too quickly, endangering US allies South Korea and Japan.