President Donald Trump said on Friday that US diplomats had a "very productive meeting" with North Korean officials, and he announced his summit later this month with North Korean leader Kim Jong Un would be held in Vietnam's capital, Hanoi. "My representatives have just left North Korea after a very productive meeting and an agreed upon time and date for the second Summit with Kim Jong Un. It will take place in Hanoi, Vietnam, on February 27 & 28," Trump said on Twitter.
"I look forward to seeing Chairman Kim & advancing the cause of peace!" he said.
Earlier this week, Trump announced the dates for the second summit with Kim and said it would be held in Vietnam, but the city had not been disclosed.
Stephen Biegun, the US special representative for North Korea, held three days of talks in Pyongyang to prepare for the summit, the State Department said on Friday.
It said Biegun had agreed with his counterpart Kim Hyok Chol to meet again ahead of the summit.
In their talks in Pyongyang, from Wednesday to Friday, Biegun and Kim Hyok Chol "discussed advancing President Trump and Chairman Kim's Singapore summit commitments of complete denuclearisation, transforming US-DPRK relations, and building a lasting peace on the Korean Peninsula," the State Department said.
Its statement, which referred to North Korea by the acronym for its official name, the Democratic People's Republic of Korea, gave no indication of any progress in the talks.
Just weeks ahead of the planned summit to follow on from an unprecedented first meeting between the leaders in Singapore last June, the two sides have appeared far from narrowing differences over U.S. demands for North Korea to give up a nuclear weapons program that threatens the United States.
Biegun said last week his Pyongyang talks would be aimed at seeking progress on commitments made in Singapore and mapping out "a set of concrete deliverables" for the second summit.
He said Washington was willing to discuss "many actions" to improve ties and entice Pyongyang to give up its nuclear weapons and that Trump was ready to end the 1950-53 Korean War, which concluded with an armistice, not a peace treaty.
Biegun said Kim Jong Un committed during an October visit by US Secretary of State Mike Pompeo to the dismantling and destruction of plutonium and uranium enrichment facilities and that "corresponding measures" demanded by North Korea would be the subject of his talks.
At the same time, he set out an extensive list of demands that North Korea would have to meet eventually, including full disclosure of its nuclear and missile programs, something Pyongyang has rejected for decades.
On Saturday, Biegun said his talks in North Korea had been productive and Trump looked forward very much to his meeting with Kim in Hanoi.
"We have some hard work to do with the DPRK between now and then," Biegun said in South Korea before a meeting with its foreign minister, Kang Kyung-wha.
"I am confident that if both sides stay committed, we can make real progress."
Trump, eager for a foreign policy win to distract from domestic troubles, has been keen for a second summit despite a lack of significant moves by North Korea to give up its nuclear weapons program. He and Biegun have stressed the economic benefits to North Korea if it does so.
"North Korea, under the leadership of Kim Jong Un, will become a great Economic Powerhouse," Trump said on Twitter.
"He may surprise some but he won't surprise me, because I have gotten to know him & fully understand how capable he is," Trump said.
Trump announced the plan for his second meeting with Kim in his annual State of the Union address on Tuesday.
Trump said much work remained to be done in the push for peace with North Korea, but cited the halt in its nuclear testing and no new missile launches in 15 months as proof of progress.
The Singapore summit yielded a vague commitment by Kim to work toward the denuclearisation of the Korean peninsula, where US troops have been stationed since the Korean War.
While in the US view North Korea has yet to take concrete steps to give up its nuclear weapons, it complains that Washington has done little to reciprocate for its freezing of nuclear and missile testing and dismantling of some facilities.
North Korea has repeatedly urged a lifting of punishing US-led sanctions, a formal end to the war, and security guarantees.