The CIA had a top secret informant close to Vladimir Putin who confirmed the Russian president’s personal involvement in hacking the 2016 US election, it has been claimed.
According to the New York Times the source was giving information to the CIA during the Obama administration.
The information, and the source, were reportedly considered so sensitive that John Brennan, the CIA director at the time, gave details to Mr Obama in an envelope, separate from the daily presidential intelligence briefing that is delivered in the Oval Office, the New York Times reported.
Mr Brennan, accompanied by the head of the National Security Agency and Mr Obama's director of national intelligence, were said to have briefed Donald Trump on the information in a meeting at Trump Tower two weeks before his inauguration.
Despite having been told about the source confirming Mr Putin's personal involvement Mr Trump went on to repeatedly question whether Russia interfered in the election.
At a joint press conference with Mr Putin in Helsinki on Monday he declined to blame the Russian president.
It was unclear whether Mr Trump knew the identity of America's Russian source, or what details of the person intelligence chiefs had given him at the Trump Tower meeting.
At the Helsinki news conference with Putin the US president was asked if he would denounce what happened in 2016 and warn Mr Putin never to do it again, and he did not directly answer.
On Wednesday he was asked in Washington whether he believed Russia is currently targeting US elections and replied "No". The White House later said his answer had been misconstrued.
On Thursday Mr Trump wrote on Twitter that he was looking forward to a second meeting with Mr Putin.
The Summit with Russia was a great success, except with the real enemy of the people, the Fake News Media. I look forward to our second meeting so that we can start implementing some of the many things discussed, including stopping terrorism, security for Israel, nuclear........
— Donald J. Trump (@realDonaldTrump) July 19, 2018
James Clapper, director of national intelligence under Mr Obama, who was present when Mr Trump was briefed on Mr Putin's personal involvement, said the incoming president had listened with "some scepticism."
Mr Clapper told CNN: "I do think there was scepticism from the get-go, from that day to this day, that indicated that anything that attacked the legitimacy, or questioned the legitimacy, of now-President Trump's election, he just couldn't get his head around."
The former intelligence chief added: "More and more I come to a conclusion after the Helsinki performance and since, that I really do wonder if the Russians have something on him."
Lindsey Graham, the Republican senator, acknowledged on Thursday that Mr Trump has had a "bad week" on Russia.
He said: "I think it's imperative that he understand that he's misjudging Putin."
In a separate development the White House announced Mr Trump had rejected a proposal, made by Mr Putin in Helsinki, that Russian investigators be allowed to question US citizens.
Those citizens included Michael McFaul, the former US ambassador to Moscow, who the Kremlin accuses of "illegal activities".
Sarah Sanders, the White House press secretary, said on Wednesday that the idea was being considered.
That sparked a widespread backlash, including from Mr McFaul who called it "crazy".
On Thursday Mrs Sanders said: "It is a proposal made in sincerity by President Putin, but President Trump disagrees with it."