US Secretary of State Mike Pompeo has met North Korean officials in Pyongyang, hoping to "fill in" details on how to dismantle the North's nuclear programme and recover the remains of US troops missing from the Korean War.
Mr Pompeo met Kim Yong-chol, who played a key role with him in arranging last month's summit between US President Donald Trump and North Korean leader Kim Jong-un in Singapore.
The talks lasted nearly three hours and it was uncertain whether Mr Pompeo would meet Mr Kim.
He will spend the night in Pyongyang, his first overnight stay in North Korea.
At the Singapore summit, Mr Kim made a broad commitment to "work toward denuclearisation", but fell short of details on how or when he would dismantle North Korea's nuclear programme, which it has pursued in defiance of UN Security Council resolutions.
"The President told me he believes that Chairman Kim sees a different, brighter future for the people of North Korea. We both hope that's true," Mr Pompeo said on Twitter after a phonecall with Mr Trump as he headed for North Korea.
Next stop: Pyongyang. I look forward to continuing my meetings with North Korean leaders. There's much hard work ahead but peace is worth the effort. pic.twitter.com/eozwL3Mx28
— Secretary Pompeo (@SecPompeo) July 6, 2018
Mr Pompeo said he was seeking to "fill in" some details on North Korea's commitments and maintain the momentum towards implementing the agreement from the summit, according to reporters.
Mr Pompeo would try to agree on at least an initial list of nuclear sites and an inventory that could be checked against the available intelligence, US intelligence officials told Reuters.
Also high on the agenda is the issue of the remains of US soldiers missing from the 1950-53 Korean War.
Mr Trump said after the Singapore summit that Mr Kim had agreed to send the remains back to the United States.
Both issues are considered essential tests of whether Mr Kim is serious about negotiations.
North Korean officials have yet to demonstrate that in working-level talks, the intelligence officials said.
