Story highlights Clapper led the intelligence community through the end of Obama's term

He rebutted Trump's assertion that others besides Russia attempted to influence the election

Washington (CNN) The former top US intelligence official on Thursday disagreed with President Donald Trump's claim that foreign actors besides Russia may have attempted to influence the 2016 presidential election.

Former Director of National Intelligence James Clapper, in an interview with CNN's Jim Sciutto on "The Situation Room," said he remains confident in the intelligence community assessment accusing Russia of attempting to bolster Trump's candidacy -- and that he knew of no evidence pointing anywhere else.

"As far as others doing this, boy, that's news to me," Clapper said. "We saw no evidence whatsoever that it was anyone involved in this other than the Russians."

Speaking to reporters in Poland ahead of the G-20 summit, Trump he thought Russia was behind the efforts, but asserted that "it could have been other people in other countries." Trump seemed to dismiss the strength of the intelligence community assessment, saying "mistakes have been made" with regard to intelligence and noting the US intelligence community's erroneous claim that Iraq under Saddam Hussein had weapons of mass destruction -- a report that the Bush administration used to make a case for war.

Clapper called the Iraq assessment a "big mistake" and said things had changed since then in the intelligence community to prevent something like that from happening.

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