April 30, 2017 1240 GMT
"I've been in public service for over 50 years — I have never seen anything like this in my lifetime," Panetta, who led the CIA from 2009 to 2011 and then the Pentagon from 2011 to 2013, told NBC in an interview aired on Friday.
Panetta said Trump was “undermining the credibility” of the very intelligence agencies that will be providing information to him as president.
He also criticized the Republican president-elect for using social media to openly question the intelligence community’s conclusion that Russia interfered in the 2016 election through cyber hacking.
“He’s going to find that it’s easy to tweet about reactions to all kinds of issues. But to seriously deal with our national security and deal with the threats to our country is a business that ought to be done in the confines of the Oval Office,” Panetta said.
Trump downplayed Russia's role in the election after he was briefed on the most recent intelligence report on the hacking on Friday afternoon. The intelligence community has concluded that the Russian government directed hackers to target various Democratic Party organizations and operatives to influence the outcome of the election.
"While Russia, China, other countries, outside groups and people are consistently trying to break through the cyber infrastructure of our governmental institutions, businesses and organizations, including the Democrat National Committee, there was absolutely no effect on the outcome of the election, including the fact that there was no tampering whatsoever with voting machines," Trump said in a statement after the meeting.
Trump has previously floated the idea that the hacks could have been carried out by a "14-year-old" or "a guy sitting on their bed who weighs 400 pounds." The president-elect has also cited past faulty intelligence involving the Iraq War to raise doubts about the intelligence community's assessment now.
"These are the same people who said Saddam Hussein has weapons of mass destruction," Trump said in a statement last month.