It started with an op-ed in The Washington Post. Under the headline “Trump is harming the dream of America more than any foreign adversary ever could,” Joe Scarborough used the 17th anniversary of the September 11th attacks to issue his latest broadside against President Donald Trump.

After giving readers an extended history lesson about 9/11 and the foreign policy disasters that have followed it, Scarborough writes, “For those of us still believing that Islamic extremists hate America because of the freedoms we guarantee to all people, the gravest threat Trump poses to our national security is the damage done daily to America’s image.”

He ended the piece by writing, “The question for voters this fall is whether their country will move beyond this troubled chapter in history or whether they will continue supporting a politician who has done more damage to the dream of America than any foreign adversary ever could.”

On Tuesday’s Morning Joe, the host got more specific, citing the retweeting of Nazis and the reaction to Charlottesville as reasons why he feels Trump is hurting the country more than terrorists ever could. “That is tearing more at the fabric of America than attacks on the Twin Towers did. We rebuilt after that, we grew stronger after that, but this, to me, seems like a far graver threat.”

“Forget about knocking down buildings in the Financial District, forget about running planes into the Pentagon,” Scarborough said. “Those are tragedies, but those tragedies bring us closer together.” Quoting New York Times columnist Roger Cohen, he added, “America is an idea. Strip freedom, human rights, democracy and the rule of law from what the United States represents to the world and America itself is gutted.”

The comments drew a sharp rebuke from, among others, Donald Trump Jr., who demanded an apology from Scarborough “to the 3000+ families who lost loved ones on this tragic day.”

Scarborough’s co-host and partner Brzezinski rushed to his defense, turning things around on Trump Jr., implying that it’s only a matter of time before Special Counsel Robert Mueller’s probe brings him down.

Earlier in the morning, during an interview with ABC News, Trump Jr. insisted that he’s not worried about potential legal jeopardy around his 2016 meeting with Russian operatives. “I’m not because I know what I did and I’m not worried about it,” he said. “That doesn’t mean they won’t try to create something.”

Scarborough has not yet responded to Trump Jr. directly, but he acknowledged on Twitter that “many have been offended” by the part of his op-ed that compared the president to the 9/11 attacks. “The column was focused on 17 years of strategic missteps,” he wrote. “The last paragraph became the sole focus of Trump supporters. On every other day of the year, I do not shy away from negative feedback from the right, the left or from Trump supporters.”

Of course, before Scarborough and Brzezinski became two of Trump’s loudest cable-news critics, they were consistently criticized themselves for being too friendly towards him during the 2016 election. As occasional Daily Beast columnist Ben Howe put it Tuesday morning: “What’s it like to know you spent years helping elevate someone that you now say is more dangerous than 9/11 terrorists, Joe?”

The host also took a moment during Tuesday’s broadcast to remind viewers what Trump said about the attacks when he called into a radio show that morning in 2001. “As the Twin Towers fell, Donald Trump chose that moment to say, ‘Well, I guess my buildings are the tallest now,'” Scarborough recalled. “He was, of course, not only extraordinarily insensitive and boorish, he was, as he is today, wrong.”