They are expected to meet again at the Sofitel Legend Metropole for one-one-one bargaining and an expanded session in which their aides will also take part. An exact schedule was not immediately announced.

It's almost certain that they will sign a document to be called by media the "Hanoi Declaration." But its wording is key amid keen attention on whether it will contain Pyongyang's plans for concrete denuclearization steps and Washington's reciprocal measures.

Kim is widely expected to seek to trade the shutdown of the Soviet-era Yongbyon nuclear complex for Trump's declaration of a formal end to the 1950-53 Korean War and some sanctions relief if possible.

Speaking to reporters about the possibility of an end-of-war declaration during a meeting with Kim, Trump said, "We'll see."

He added he has not walked back from his pledge to denuclearize the secretive communist nation, which he described as having "tremendous economic potential."