CIA director Mike Pompeo forged a “good relationship” with North Korean leader Kim Jong-un when they met last week, US President Donald Trump has tweeted.
Confirming media reports of the secret meeting in Pyongyang, Mr Trump said it had gone “very smoothly”.
The surprise visit marks the highest-level contact between the United States and North Korea since 2000.
Mr Trump is expected to hold a summit with Mr Kim by June. Details are being worked out, the US president said.
South Korea has also signalled that it may pursue a formal resolution of the longstanding conflict on the peninsula. President Moon Jae-in and Mr Kim are due to meet next week.
The US president earlier gave his “blessing” for the talks between the South and North to discuss a peace treaty to formally end the 1950-1953 Korean War.
What do we know about the ‘secret meeting’?
The news that Mr Pompeo had travelled to North Korea for a clandestine meeting with Mr Kim was first reported by The Washington Post on Tuesday.
The trip took place after Mr Pompeo was nominated by Mr Trump to replace Rex Tillerson as secretary of state, sources told the newspaper.
Later, Reuters news agency carried a similar report. Early on Wednesday, Mr Trump confirmed the news with a tweet.
Very little is known about the talks other than that they were to prepare for the forthcoming Trump-Kim summit.
Mr Pompeo is predicted to be confirmed as the top US diplomat by the Republican-controlled Senate in the coming weeks.
How do the US and North Korea communicate?
The US does not have diplomatic relations with North Korea, although diplomats have visited in the past and so-called “back channels” are used to communicate with Pyongyang.
The last senior US official to meet a North Korean leader was Madeleine Albright, who was secretary of state when she travelled to Pyongyang for talks with Kim Jong-il, the father of the current leader.