The U.S. envoy and North Korean representatives are slated to meet one more time before Trump and Kim's summit. He said the US Special Representative for North Korea, Stephen Biegun, is now in Pyongyang and is holding talks with his counterpart, Kim Hyok Chol.
The US wants North Korea to make a full declaration of all its nuclear weapons facilities and commit to destroying them, under global supervision - something North Korea has never said it will do.
It has been confirmed in a United Nations study by experts that the North sold fishing rights to Chinese fishery operators to earn foreign currency, an act viewed as an evasion of United Nations sanctions. He is expected to brief South Korean officials about his visit to North Korea over the weekend.
The US envoy for North Korea has returned from Pyongyang, where he held talks to prepare for a second US-North Korean leadership summit.
Mr Trump said his representatives had a "productive meeting" and that he was looking forward to advancing peace.
But for liberal South Korean President Moon Jae-in, who is eager to push ahead with ambitious plans for engagement with North Korea, a breakthrough in Vietnam is crucial.
He belongs to the regime's State Affairs Commission, a government body that Kim Jong-un heads.
The Singapore summit yielded a vague commitment by Kim to work toward the denuclearization of the Korean peninsula, where US troops have been stationed since the Korean War.
But North Korea said previous year that February 8 would be celebrated as the date that the Korean People's Army was founded, as that is the day in 1948 that Kim Il Sung began a transformation that culminated in its establishment.
Both sides said they were committed to denuclearisation, but with no details of how this would be carried out or verified.
The anniversary of the founding of the North Korean army was previously marked on April 25, the day in 1932 when Kim Il Sung launched the first revolutionary army.
Trump had branded the North Korean leader Kim Jong-un "Little Rocket Man" and later told Fox News's Sean Hannity it was part of a strategy to bring Kim to the table.
The North must immediately disclose its nuclear and missile programs.
It seems, out of two potential venues - Hanoi and Da Nang - the two sides narrowed it down to Hanoi. "President is very much looking forward to taking next steps".