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(CNN) —  

Former US intelligence chiefs expressed astonishment and condemnation Monday in response to President Donald Trump’s comments at Monday’s news conference with Russian President Vladimir Putin, with former CIA Director John Brennan calling the US President’s performance “nothing short of treasonous.”

Following his one-on-one meeting with Putin in Helsinki, Finland, Trump declined to endorse the US intelligence community’s assessment that Russia interfered in the 2016 election over Putin’s denial, saying the Russian President was “extremely strong and powerful” in his denial.

“Donald Trump’s press conference performance in Helsinki rises to & exceeds the threshold of ‘high crimes & misdemeanors.’ It was nothing short of treasonous,” Brennan, a frequent critic of Trump who served as CIA chief from 2013 through January 2017, tweeted during the event. “Not only were Trump’s comments imbecilic, he is wholly in the pocket of Putin. Republican Patriots: Where are you???”

Former Defense Secretary Chuck Hagel said Trump “failed America today,” but stopped short of calling the President’s behavior “treasonous.”

“I would not have said it the way John (Brennan) said it. John can say it the way he wants to say it. But as to impeachment, we’ll see how this plays out. That’s a congressional responsibility and the Congress must do what they think is in the best interest of this country,” Hagel told CNN’s Wolf Blitzer.

The Obama-era defense secretary said that Trump didn’t appear to have a strategy.

“This was not a golf outing. This was not a real estate transactional kind of arrangement. … Engagement must be connected to a strategic interest, a strategic purpose. I don’t know what that strategic purpose was. I am now convinced we didn’t have one,” Hagel said, later remarking that the meeting with Putin marked “a sad day for America” and “a sad day for the world.”

Another former defense secretary, Ash Carter, said the news conference was “like watching the destruction of a cathedral.”

“In my almost four decades with national defense starting in the Pentagon under Ronald Reagan, I never saw or imagined so uneven a handover of American security interests and principles with nothing in return at a meeting,” Carter said in a statement.

Former Director of National Intelligence James Clapper, who served during the Obama administration, called the news conference “truly unbelievable.”

“On the world’s stage, in front of the entire globe, the President of the United States essentially capitulated and seems intimidated by Vladimir Putin. So it was amazing and very, very disturbing,” Clapper, a CNN national security analyst, told Anderson Cooper Monday afternoon.

Former CIA and National Security Agency Director Michael Hayden, who led the NSA during the final years of George W. Bush’s presidency, also expressed dismay over the President’s performance.

In one tweet, Hayden expressed agreement with an analysis that Trump believes Putin more than American intelligence agencies. And when another user tweeted “holy f****n s**t” following the news conference, Hayden responded, “I agree.”

CNN’s Michael Callahan, Meg Wagner, Sheena McKenzie and Brian Ries contributed to this report.