Trump Suggests, Without Evidence, That CIA Director Is 'Leaker' Behind Unsubstantiated Report The CIA director also said Trump needs to be careful in his approach to Russia.

 -- In an unprecedented escalation of a feud between the incoming president and U.S. intelligence community, President-elect Donald Trump suggested Sunday that outgoing CIA Director John Brennan could be behind the leak of an unsubstantiated report alleging Russia holds compromising information on Trump.

Trump cited critical comments by Brennan in an interview Sunday with Fox News, where Brennan suggested Trump's desire to repair relations with Russia showed he "does not fully understand" the threat the country poses to the United States.

Trump then took to Twitter to ask his more than 19 million followers whether the CIA director was the "leaker of Fake News."

Trump has in the past two weeks accused the intel heads who provided him with the classified briefing on Russia's interference in the U.S. election of leaking the dossier that includes salacious unsubstantiated details that a former MI6 official alleges he obtained from Russian sources.

But his targeting of Brennan is the first time he has called out a specific member of the intel community.

The tweets are a reaction to Brennan cautioning the president-elect to be "very disciplined" with what he says publicly and recognize his words have an impact on U.S. national security once he takes office.

"I think Mr. Trump has to be very disciplined in terms of what it is that he says publicly. He is going to be, in a few days' time, the most powerful person in the world in terms of sitting on top of the United States government and I think he has to recognize that his words do have impact," CIA Director John Brennan said today on "Fox News Sunday."

According to Brennan, "there are many dangers" when a president-elect and the intelligence community are at odds. In recent days, Trump has accused the intelligence community of leaking the unverified 35-page dossier on alleged Trump-Russia relations, even going as far as to compare US intelligence to Nazi Germany.

"If he doesn't have confidence in the intelligence community, what signal does that send to our partners and allies, as well as our adversaries?" Brennan asked.

Brennan, who reaches the end of his term Friday, also fired back at Trump's comparison of the U.S. intelligence community to Nazi Germany as "outrageous."

"What I do find outrageous is equating the intelligence community with Nazi Germany," Brennan said. "I do take great umbrage at that, and there is no basis for Mr. Trump to point fingers at the intelligence community for leaking information that was already available publicly."

When asked if Trump understands the threat from Russia, Brennan told Fox News, "I don't think he has a full appreciation of Russian capabilities, Russia's intentions, and actions that they are undertaking in many parts of the world."

Brennan added, "Mr. Trump needs to understand that absolving Russia of the various actions it has taken in the past number of years is a road that he, I think, needs to be very, very careful about moving down."

The Trump transition team did not respond to a request for comment on Brennan's remarks today.

Twice during the interview, the CIA director stressed that he feels Trump needs to understand that it's "more than being about him and it's about the United States and the national security."

"He has to make sure that now he's going to have the opportunity to do something for national security - as opposed to talking and tweeting - he's going to have tremendous responsibility to make sure that U.S. national security interests are protected and are advanced," Brennan said.

Brennan warned, "Spontaneity is not something that protects national security interests. And so, therefore, when he speaks, when he reacts, just to make sure he understands that the implications and impact on the United States could be profound."

During the interview, he would neither confirm nor deny whether the CIA has information on whether the Trump transition team has had contact with Russia -- something the Trump team has denied.