The departing CIA director John Brennan has given a damning appraisal of Donald Trump, warning the President-elect does not fully understand the threat posed to the US by Russia.

Speaking to Fox News with five days to go until Mr Trump is sworn in as the 45th President of the US, Mr Brennan said the billionaire businessman’s forthright “talking and tweeting” are not in the country’s best interests.

Mr Brennan’s comments highlighted the ongoing tension between the President-elect and the intelligence services, after the leaking of unverified raw intelligence alleging close ties between Mr Trump and Russia.

In a series of tweets after those explosive allegations were made public, Mr Trump appeared to blame the intelligence agencies for letting the dossier be released. He wrote: “Are we living in Nazi Germany?”

Mr Brennan told Fox News Sunday that Mr Trump had indeed been briefed about the allegations before they were reported by CNN, despite the President-elect’s advisers saying he was not aware of them.

“What I do find outrageous is equating intelligence community with Nazi Germany,” Mr Brennan said. “I do take great umbrage at that.

“There is no basis for Mr Trump to point fingers at the intelligence community for ‘leaking’ information that was already available publicly,” he added.

The CIA director, who will likely be replaced by Mr Trump’s pick Mike Pompeo, advised the incoming President not to forgive Russia for its recent transgressions and warned him to watch his words and actions.

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

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“It’s more than just about Mr Trump. It’s about the United States of America.”

Speaking earlier on Sunday, President Barack Obama’s chief of staff said the president had sought an assessment on any interference in the 2016 election so that policymakers could address the issue.

Denis McDonough said it was “important for the president that we get a full assessment” to brief policymakers so they can “implement policies to make sure that doesn’t happen again”.

Mr Trump has lashed out at those who have suggested his win was aided by Russian involvement.