CIA Director John Brennan has warned President-elect Donald Trump to avoid off-the-cuff remarks once he takes office.
The outgoing CIA chief said spontaneity was not in the interests of national security.
Donald Trump is known for regularly making broad pronouncements on issues of national importance on his Twitter feed.
John Brennan also said that Donald Trump did not fully appreciate Russia’s capabilities or intentions.
He said: “I think Mr. Trump has to understand that absolving Russia of various actions that it’s taken in the past number of years is a road that he, I think, needs to be very, very careful about moving down.”
John Brennan’s remarks, in an interview for Fox News Sunday, come a week after the release of a US intelligence report which said Russian President Vladimir Putin had likely attempted to influence the election.
Donald Trump is considered to have underplayed for months the conclusions of the intelligence community that Moscow hacked Hillary Clinton’s campaign. The president-elect only accepted them at a news conference on January 11.
Meanwhile both the Kremlin and Donald Trump’s team have denied reports in the Sunday Times that the two sides were planning a summit between Donald Trump and Vladimir Putin in the Icelandic capital Reykjavik.
Reykjavik was the venue for a summit in 1986 – near the end of the Cold War – between Ronald Reagan and Mikhail Gorbachev, the then US and Soviet leaders.
John Brennan said “talking and tweeting” was not an option for Donald Trump, who takes office on January 20.
“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,” he said.
“It’s more than just about Mr. Trump. It’s about the United States of America.”
John Brennan also took Donald Trump to task for accusing the intelligence services of leaking an unverified dossier which suggests Russian security officials have compromising material on him, which could make him vulnerable to blackmail.
“What I do find outrageous is equating the intelligence community with Nazi Germany,” the CIA chief said, referring to a tweet by Donald Trump on January 11.
“There is no basis for Mr. Trump to point fingers at the intelligence community for leaking information that was already available publicly.”
However, Donald Trump responded with tweets quoting veteran Washington Post journalist Bob Woodward, who told Fox News Sunday that the dossier should never have been presented at an intelligence briefing and that the intelligence services should apologize for their mistake.
The media should also apologize, Donald Trump added.
Donald Trump has described the claims as “fake news” and “phoney stuff”.
Russia also denies the existence of the dossier and says allegations that it ran a hacking campaign to influence the elections are “reminiscent of a witch-hunt”.