While admitting that dealing with North Korea was "going to be a process", Trump said he believed the effort would ultimately be "successful".
The June 12 meeting in Singapore, the first between heads of the technically still-warring nations, is meant to begin the process of ending North Korea's nuclear program, and Trump said he believes Kim is committed to that goal.
Yet he also said a news conference that hard work remains including hurdles that may appear to be insurmountable as negotiations progress on the US demand for North Korea's complete, verifiable and irreversible denuclearization. The US has "hundreds of new sanctions that are ready to go" but isn't going to implement them while talks are ongoing.
"That letter was a very nice letter", Trump said to reporters.
Kim Yong Chol arrived in Washington from NY, where he met with Pompeo on preparations for the planned June 12 encounter between the USA and North Korean leaders in Singapore.
USA officials with knowledge of the letter's contents said it did not make any noteworthy threats or concessions, and was seen as a positive step, according to multiple news reports.
Trump said one possible outcome of the summit might be an end to the Korean War. He also said it was likely that more than one meeting would be necessary.
He added: "I may be in for a big surprise, folks".
Senate Majority Leader Mitch McConnell (R-Ky.) in Louisville warned Trump to be dispassionate about North Korea. He is the highest-ranking North Korean official to visit the U.S.in 18 years, and his trip to the White House will be a highly symbolic sign of easing tensions after fears of war escalated amid North Korean nuclear and missile tests last year.
During the 2018 Olympics in Pyeongchang, South Korea set aside $2.6 million to cover travel accommodations for a North Korean cheering squad, an art troupe and other members of the visiting delegation.
The North Korean envoy, a close confidant of Kim Jong-un, arrived in Washington after two days of talks with US Secretary of State Mike Pompeo in NY.
Trump had called off plans for a summit in a letter to Kim on May 24, complaining of "the tremendous anger and open hostility" in comments from North Korea.
When it comes to paying for lodging at North Korea's preferred 5-star luxury hotel, the United States is open to covering the costs, the two people said, but it's mindful that Pyongyang may view a US payment as insulting.
Despite the upbeat messaging in the United States, Kim Jong Un, in a meeting with Russia's foreign minister on Thursday, complained about the USA trying to spread its influence in the region, a comment that may complicate the summit. But there are lingering doubts on whether he will ever fully relinquish his nuclear arsenal, which he may see as his only guarantee of survival in a region surrounded by enemies. North Korea's conciliatory response to that letter appears to have put the summit back on track.
Kim Yong Chul, who till now was under United States sanctions, is likely to stay in the country till tomorrow.