US Secretary of State Mike Pompeo said on Thursday that North Korean leader Kim Jong Un told him personally that he is "prepared to denuclearize".
President Donald Trump said on Thursday he hoped someday US relations with Kim's secretive Pyongyang government could be normalized.
The main issue for the June 12 summit in Singapore is the US demand for North Korea to abandon a nuclear weapons program that now threatens the United States. North Korea has rejected giving up its arsenal unilaterally.
North Korea defends its nuclear and missile programs as a deterrent against what it sees as US aggression. The United States stations 28,500 troops in South Korea, a legacy of the Korean War.
Trump said he would quit the talks if he felt he must, and would ramp up US sanctions pressure on North Korea if the talks did not go well.