US Secretary of State Mike Pompeo arrived in Pyongyang Friday to press Kim Jong-un for a more detailed commitment to denuclearisation following the North Korean leader's historic summit with President Donald Trump.
Pompeo was greeted in the North Korean capital by Kim's right-hand man Kim Yong Chol and Foreign Minister Ri Yong Ho.
Since meeting Kim in Singapore last month Trump has been bullish about hopes for peace, boasting that the threat of nuclear war is over.
But the statement the leaders signed was short on clear commitments.
Kim agreed to the "complete denuclearisation of the Korean Peninsula" - a stock phrase favoured by Pyongyang that stops short of longstanding US demands for North Korea to give up its atomic arsenal in a "verifiable" and "irreversible" way.
Pompeo has been tasked with negotiating a plan that Washington hopes would involve Kim declaring the extent of his nuclear weapons programme and agreeing a timetable for it to be dismantled.
"Our leaders made commitments at the Singapore summit on the complete denuclearisation of North Korea," Pompeo had earlier told reporters travelling with him.
"On this trip, I'm seeking to fill in some details on those commitments and continue the momentum toward implementation of what the two leaders promised each other and the world," he said.
"I expect that the DPRK is ready to do the same," he added, using the initials of North Korea's official name.
Kim Yong Chol welcomed Pompeo to North Korea, noting that it was his third visit to the country.
"The more we meet, the deeper our friendship will be, I hope," he said. "The more you come, the more trust we can build between one another."
The top US diplomat, who will be staying overnight in the North Korean capital for the first time, said he looked forward to a "very productive" encounter.
In a tweet, before he landed in Pyongyang, Pompeo said he was "looking forward to continuing our work toward the final, fully verified denuclearisation of #DPRK, as agreed to by Chairman Kim".
Washington hopes that "complete" denuclearisation can begin within a year, but many expert observers and Trump critics warn that Kim's summit promise meant little and the process could take years - if it ever starts.
In the meantime, Pompeo and Trump have vowed to keep in place the international economic sanctions that they believe forced the North to the negotiating table in the first place.
Shortly after arriving in Pyongyang, Pompeo laughed off reports in the South Korean press that he was carrying an Elton John CD.
Chosun Ilbo, citing unnamed Washington sources, said the "Rocket Man" CD was a gift for Kim Jong Un - a reference to Trump's "Little Rocket Man" jibe of last year.
After talks late Friday and early Saturday in the capital, Pompeo is due to fly on to Tokyo to brief his Japanese and South Korean counterparts.
His round-the-world diplomatic voyage will then take him on to Vietnam and Abu Dhabi before he arrives in the Belgian capital Brussels to rejoin Trump for next week's NATO summit.
