As far as the US definition of denuclearization, Biegun said a few times that it would involve a comprehensive removal of all elements of North Korea's WMD program.

Pyongyang has rejected making an itemized declaration of its weapons programs for decades.

Last week, South Korean Foreign Minister Kang Kyung-wha told Reuters at the World Economic Forum in Davos that North Korea could show its commitment to denuclearization by shutting its Yongbyon complex and allowing worldwide inspections to confirm that. "Meetings are going well with good intent and spirit on both sides. And I think they really want to do something, and we'll see", he said, adding that the date and location of their meeting would be announced early next week, probably during his State of the Union address on Tuesday.

On Wednesday, Secretary of State Mike Pompeo revealed he has sent a team to an undisclosed Asian country to begin laying the foundation for the upcoming meeting.

USA and North Korean officials plan to meet for talks in Pyongyang after the Lunar New Year to iron out details of the second bilateral summit scheduled for late February.

United States president Donald Trump and North Korean president Kim Jong-un.

Pyongyang has been demanding that the USA take steps corresponding to its denuclearization measures, but the United States maintains that the North's steps have been insufficient and that sanctions will remain until complete denuclearization is achieved.

The United States is seeking to achieve "a set of concrete deliverables" through working-level negotiations with Pyongyang ahead of the scheduled leaders' summit, said US envoy to the Democratic People's Republic of Korea (DPRK) on Thursday.

"I have this ideal outcome moment where the last nuclear weapon leaves North Korea, the sanctions are lifted, the flag goes up in the embassy and the treaty is signed in the same hour", Biegun said at Stanford University. Trump said that since ending the "terrible Iran Nuclear Deal, they are MUCH different, but a source of potential danger and conflict".

The White House called off President Donald Trump's daily intelligence briefing on Wednesday a day after CIA Director Gina Haspel and Director of National Intelligence Dan Coats, as well as a handful of other top intelligence officials presented their assessment of national security threats in front of Congress that appeared to contradict the administration's recent claims, The Daily Beast reported.

Speaking weeks before Trump is due to meet the North Korean leader Kim Jong-un in a second summit, Biegun said the denuclearisation process relied on Pyongyang providing a detailed account of its nuclear and missile programmes.

But envoy Stephen Biegun also set out an extensive list of demands for the North, including a full disclosure of its weapons program.

But there are still sceptics on the Korean peninsula and in the US.

And finally, Trump does not consider ISIS as much of a threat as it used to be before his presidency, despite apprehensions from the intelligence community.

"We are not involved in any diplomatic discussion that would suggest this trade off".