Trump is in for a 'rude awakening' on Putin, ex-senator and diplomat George Mitchell warns

Intelligence 'skepticism' all around: George Mitchell

President-elect Donald Trump's skepticism about U.S. intelligence conclusions that Russian-led hacking was aimed at disrupting the election is misdirected, former Senate Majority Leader George Mitchell told CNBC on Thursday.

Mitchell, a veteran Democrat and a former diplomat, said on "Squawk Box" that Trump should err on the side of American intelligence, rather than denials from Russian President Vladimir Putin and WikiLeaks founder Julian Assange.

A Senate Armed Services Committee hearing on Thursday about cyber-threats is expected to be dominated by the alleged role of Russia in trying to help get Trump elected.

In appearing to side with Russia, Trump is in for a "rude awakening, because Vladimir Putin does not wish the United States well," Mitchell warned.

"[Putin] sees the United States as the perpetrator of a great tragedy upon the Soviet Union and Russia," Mitchell said. "He has said that the greatest catastrophe in recent years was the demise of the Soviet Union."

President Barack Obama is expected on Thursday to be brought up to speed on an intelligence report he requested on potential Russian cyberattacks on elections dating back to 2008.

Trump is set to receive an intelligence briefing on Friday in New York.