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 over Easter weekend, unnamed officials told the Washington Post and Reuters.
Earlier Mr Trump acknowledged the US had held direct talks at high levels.
He was speaking as he hosted Japanese Prime Minister Shinzo Abe in Florida.
“We have had direct talks at… extremely high levels,” he said, adding that five locations were being considered for the Kim Jong-un meeting.
There have been fears in Tokyo that Mr Trump’s plans for bilateral talks could sideline Japan, a key US ally and neighbour of North Korea.
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Relations between the two men appeared cordial. It is the second time Mr Trump has welcomed Mr Abe to his Mar-a-Lago resort and they are expected to fit in another round of golf, a shared passion.
It is a break for the two men who are both battling pressure at home: Mr Abe is facing cronyism claims while Mr Trump has been dogged by a Justice Department inquiry into alleged Russian meddling in the 2016 US election, claims he had an affair with an adult film star, and scathing attacks by a former FBI director on a book tour .
When will the summit take place?
Mr Trump surprised the international community last month by accepting Pyongyang’s suggestion for direct talks.
It would be unprecedented for a sitting president to meet a North Korean leader.
Mr Trump said the summit would take place either in early June or “a little before that”.
North Korea has been isolated for decades because of its well-documented human rights abuses and its pursuit of nuclear weapons, in defiance of international laws and UN sanctions.
It has carried out six nuclear tests, and has missiles that could reach the US.
But South Korea’s hosting of the Winter Olympics this year gave an unexpected window for diplomacy.
Is the US relationship with Japan still special?
Mr Trump insisted on Tuesday that the two countries were “very unified on the subject of North Korea”.
However, observers say Mr Abe’s goal for his US trip will be to persuade the US president as much as he can not to sway from the West’s hard line on Pyongyang.
The Japanese prime minister has repeatedly sought to portray a close personal relationship with Mr Trump and was the first foreign leader to meet him in New York after his election victory in 2016.
On trade, Mr Abe wants exemptions from Mr Trump’s recent steel and aluminium tariffs but President Trump is unhappy with Japanese trade practices and is expected to press for concessions.
The Trump administration’s America First policy has already led to Washington leaving the Trans-Pacific Partnership (TPP), a vast trade deal between countries in Asia and the Americas.
However, late last week Mr Trump suddenly floated the idea of maybe joining the TPP after all.