CIA director Mike Pompeo travelled to Pyongyang for a secret meeting with North Korean leader Kim Jong-un, US media report.
The meeting to prepare for direct talks between US President Donald Trump and Mr Kim took place on about 1 April, unnamed officials said.
Mr Trump had earlier alluded to high-level direct talks with Pyongyang.
But this unexpected and clandestine meeting would mark the highest level US contact with North Korea since 2000.
“We have had direct talks at… extremely high levels,” Mr Trump said from Florida, where he is hosting Japan’s Prime Minister Shinzo Abe.
The president added that he gave his “blessing” for talks between the South and North to discuss a peace treaty to formally end the 1950-1953 Korean War.
South Korea has also signalled that it may pursue a formal resolution of the conflict. South Korea’s President Moon Jae-in and Mr Kim are scheduled to meet at the end of April.
The news that Mr Pompeo had travelled to North Korea for a clandestine meeting with Mr Kim was first reported by The Washington Post.
The trip took place shortly after Mr Pompeo was nominated by Mr Trump to replace Rex Tillerson as secretary of state, two anonymous sources “with direct knowledge of the trip” told the newspaper.
Later the Reuters news agency said the report had been confirmed to them by senior officials. The White House has not commented.
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 coming weeks.
This is despite mounting speculation that he will, unusually, fail to receive the backing of the bipartisan Senate Foreign Relations Committee following a grilling of more than five hours by the committee last week.
The US does not have diplomatic relations with North Korea, although diplomats have visited in the past and there are some so-called “back channels” used to communicate with Pyongyang.