“It’s really upset people across the partisan divide in ways that I have not seen in years,” Colbert said of the meeting.
Colbert continued: “These are the worst reviews I’ve ever seen since Titanic … and I’m not talking about the movie.”
The Late Show host went on to say that Trump’s behaviour “unnerved a lot of people,” and he showed a tweet from former CIA director John Brennan, who criticized Trump for being “wholly in the pocket of Putin.”
Brennan also asked, “Republican Patriots: Where are you?”
“That’s an excellent point,” Colbert said. “That’s worth asking. Where are they?”
Sen. John McCain also criticized Trump on Twitter, saying that “the damage inflicted by President Trump’s naiveté, egotism, false equivalence and sympathy for autocrats is difficult to calculate.”
Colbert pulled out a calculator to assess the formula for Trump’s behaviour during the summit. “OK, egotism plus naiveté times false equivalence equals … yeah, treason,” Colbert said.
The late-night host also admitted that the Helsinki summit had shaken him “to his core,” and encouraged his audience to stand up against Trump’s behaviour.
Colbert showed a clip of the Trump-Putin press conference in which the Russian president asked if reporters believe the Russian government would try to obtain compromising information on 500 American businessmen attending a meeting in St. Petersburg, including Trump.
“Do you think we tried to collect compromising information on each and every single one of them?” Putin asked the press.
WATCH: ‘The president isn’t leading’: Republican senator slams Trump over summit with Putin
Colbert responded to Putin’s question saying, “Yeah. Yeah, I do. When I was in Russia – and this is true – I was followed everywhere I went and I’m a comedian. All right? I was informed by our security people in no uncertain terms that my phone was bugged and my room had cameras in it. So I showered in a blue blazer. When I finally, when finally I had to get naked eventually – and this is true – I turned to every mirror and said, ‘You like, Ivan? You like?’”
Watch part of Colbert’s monologue from Monday night in the video above.
The Late Show with Stephen Colbert airs weeknights at 11:35 p.m. on Global.