North Korea can look forward to “a future brimming with peace and prosperity” if it agrees to quickly give up its nuclear weapons, US secretary of state Mike Pompeo has pledged.

The US aspires to have North Korea as a “close partner” and not an enemy, Mr Pompeo said, noting that throughout history America has become good friends with former adversaries.

Mr Pompeo said he had told North Korean leader Kim Jong-un of that hope during his brief visit to Pyongyang earlier this week, during which he finalised details of the 12 June summit between Mr Kim and Donald Trump and secured the release of three Americans imprisoned in the country.

He said his talks with Mr Kim on Wednesday had been “warm,” ‘’constructive” and “good” and that he made clear that if North Korea gets rid of its nuclear weapons in a permanent and verifiable way, the US is willing to help the impoverished nation boost its economy and living stands to levels like those in prosperous South Korea.

“We had good conversations about the histories of our two nations, the challenges that we have had between us,” Mr Pompeo told reporters at a news conference Friday with South Korea’s visiting foreign minister, Kang Kyung-wha. “We talked about the fact that America has often in history had adversaries who we are now close partners with and our hope that we could achieve the same with respect to North Korea.”

He did not mention other adversaries by name, but Mr Pompeo and others have often noted that the US played a major role in rebuilding Japan and the European axis powers in the wake of the Second World War.

“If North Korea takes bold action to quickly denuclearise, the United States is prepared to work with North Korea to achieve prosperity on the par with our South Korean friends,” he said.

Ms Kang praised the upcoming meeting between Mr Trump and Mr Kim in Singapore as a “historic” opportunity, but added a few notes of scepticism as well. Amid concerns that North Korea will demand the US withdraw its troops from neighbouring South Korea, Ms Kang emphasised that the US military presence there must be “a matter for the US – [South Korea] alliance first and foremost.”

She said the US troop presence in the South for the past 65 years has played a “crucial role for deterrence,” peace and stability on the Korean peninsula. Therefore, she said, any change in the size of the US forces in South Korea should not be on the table at the summit.

“The next few weeks will be critical, requiring air-tight coordination between our two countries,” Ms Kang said, noting that South Korean President Moon Jae-in would be in Washington to see Mr Trump later this month.

Since Mr Trump announced plans to hold a summit with Mr Kim, questions have been raised continually about whether the two leaders have the same objective in mind when they speak about “denuclearisation”.

To the US, that means the North giving up the nuclear weapons it has already built. But North Korea has said it is willing to talk now because it’s already succeeded in becoming a nuclear-armed state, fuelling skepticism that the North would truly be willing to give those weapons up.

Mr Pompeo said there would need to be “complete” and “verifiable” denuclearisation that would remove North Korea as a threat to the South, the US and the rest of the world. He said a major inspection and monitoring regime would be required to ensure the North’s compliance.

“I think there is complete agreement about what the ultimate objectives are,” Mr Pompeo said, though he declined to offer more detail.