One week before he is inaugurated as US president, Trump has been rocked by the dossier.
A week before he enters the White House, Donald Trump has picked a high-risk fight with the all-important US intelligence community, blaming it for an incendiary but unsubstantiated report on his alleged Moscow ties and lurid behavior in Russia.
Trump on Wednesday accused US spies of leaking the report, a dossier prepared for US politicians by a British private consultant, to the media to sabotage him, calling it a "disgraceful" act worthy of Germany's Nazi regime.
The outburst prompted a late night call from National Intelligence Director James Clapper, who told the president-elect he did not believe the leak came from the intelligence agencies.
"I emphasized that this document is not a US Intelligence Community product and that I do not believe the leaks came from within the IC," Clapper said in a statement.
One week before he is inaugurated as US president, Trump has been rocked by the dossier, which a former British MI6 intelligence agent prepared originally as opposition research for other US politicians.
The 35-page report alleges longstanding communications between Russian officials and Trump's Republican campaign, and that Russian intelligence holds salacious videos involving Trump and prostitutes in Russia.
None of the allegations have been substantiated, but they were considered serious enough for US intelligence to investigate them and include its own conclusions in a top secret briefing to Trump last Friday on Russia's meddling in the US election, including the hacking of Democratic Party computers.
Trump exploded after media reported Tuesday that some of the dossier's allegations were included in the briefing, which was presented by Clapper with the heads of the CIA, FBI and National Security Agency.
That lent the dossier some credibility, and it was then published online by BuzzFeed, adding to the president-elect's outrage.
"Intelligence agencies should never have allowed this fake news to 'leak' into the public. One last shot at me. Are we living in Nazi Germany?" Trump tweeted early Wednesday.
He repeated the accusation hours later in a press conference.
"I think it was disgraceful -- disgraceful that the intelligence agencies allowed any information that turned out to be so false and fake out."
"I think it's a disgrace, and I say that -- and I say that, and that's something that Nazi Germany would have done and did do."
His blasts against the intelligence community came after his repeated rejections of their conclusion that Russia had interfered with last year's election, a position he appeared to reverse on Wednesday.
Clapper, whose office coordinates 16 other spy agencies, did not comment in his statement on the specifics of the dossier or on Friday's Trump briefing.
But analysts say the four spy chiefs would not have raised the dossier in their briefing for Trump if they saw it as entirely unfounded.
"Part of our obligation is to ensure that policymakers are provided with the fullest possible picture of any matters that might affect national security," Clapper said.
Trump's attacks on the intelligence community left him appearing increasingly isolated. As president he will depend on Clapper's successor as Director of National Intelligence as well as the CIA chief for regular classified updates on threats to the United States.
White House spokesman Josh Earnest said impugning the integrity of the intelligence services was "deeply misguided."
"Doesn't mean they're always right, but questioning their motives is another thing altogether," he said Wednesday.
Trump's own pick to lead the CIA, Congressman Mike Pompeo, defended the agency Wednesday and said he did not question the official intelligence assessment that Putin ordered the unprecedented election interference.
"I see nothing to cast any doubt on the findings in the report," he said.
Asked if the CIA is politicized, as Trump charged, he replied: "In my experience I have not seen that."
Author of dossier respected
Meanwhile in London people who know Christopher Steele, the former MI6 agent turned private consultant identified as the author of the report on Trump and Russia, said he is well regarded in espionage circles.
"I do know these guys and they have a good reputation. There's no way they would have made up the dossier," a source close to the British intelligence services told AFP.
"The idea his work is fake or a cowboy operation is false, completely untrue," the Guardian quoted a former Foreign Office official and friend of Steele's as saying.
"He's not the sort of person who will simply pass on gossip. If he puts something in a report, he believes there's sufficient credibility in it for it to be worth considering."