WASHINGTON (WASHINGTON POST) - President Donald Trump's national security adviser suggested on Sunday (April 29) that the United States isn't ready to ease sanctions or offer other concessions to North Korea before Pyongyang fully commits to denuclearisation.

"I think that's what denuclearisation means," Ambassador John Bolton said during an interview on Fox News Sunday.

He later said that the Trump administration isn't "starry-eyed" when it comes to North Korean President Kim Jong Un's recent promises.

Mr Bolton cited a similar arrangement the United States brokered with Libya in 2003 that resulted in the country relinquishing its weapons, as well as a 1992 pact between North and South Korea under which Pyongyang was to have given up "any aspect of nuclear weapons", he said, including uranium enrichment.

"Now we've got other things to talk about, as well - ballistic missiles, chemical and biological weapons, the American hostages, the Japanese abductees," Mr Bolton later said. "But starting on the nuclear side with what North Korea agreed to nearly a quarter-century ago is a pretty good place to start."

Mr Bolton's comments on Sunday come two days after Mr Kim and his South Korean counterpart issued a rare joint statement committing to "complete denuclearisation of the Korean Peninsula".

Since then, South Korean leaders have said that North Korea would be open to allowing security experts and journalists to observe the closure of one of the North's key test sites.

In the meantime, the White House continues to prepare for an upcoming meeting between Mr Trump and Mr Kim.

"Things are going very well, time and location of meeting with North Korea is being set," Mr Trump tweeted on Saturday.

Mr Bolton said on Fox News Sunday that the details are still being negotiated.

"We need to agree on a place, and that remains an issue," he said. "But if, in fact, Kim has made a strategic decision to give up his entire nuclear weapons programme, then I think deciding on the place and the date should be fairly easy."

He later said that the statement from the North and the South calling for denuclearisation of the entire Korean Peninsula might not affect the United States or require it to remove its military assets from the region, explaining that Washington officials "certainly haven't made that commitment".

Already, Mr Trump's newly confirmed Secretary of State, Mr Mike Pompeo, has huddled with the North Korean leader.

"My goal was to try and identify if there was a real opportunity there. I believe there is," Mr Pompeo said on Sunday on ABC News's This Week.

Asked about potential outcomes, Mr Pompeo said he "talked about getting the release of the American detainees. And then we talked a great deal about what it might look like, what this complete, verifiable, irreversible mechanism might look like."

Yet he declined to say whether there would be any reward for North Korea - perhaps in the form of sanctions relief - if it took additional, early steps toward dismantling its nuclear programme.

"We have our eyes wide open," Mr Pompeo said multiple times.