President Trump’s lawyers sent a letter to former White House chief strategist Steve Bannon on Wednesday night, insisting he stop making derogatory comments about Trump and his family.

The letter comes after excerpts from a forthcoming book, "Fire and Fury: Inside the Trump White House" by Michael Wolff, were published Wednesday and featured unflattering comments from Bannon about the Trump family.

Bannon along with other staffers in Trump's campaign had signed nondisclosure agreements requiring them to not make any derogatory comments toward Trump, his family, the campaign, or the Trump Organization.

“You [Bannon] have breached the Agreement by, among other things, communicating with author Michael Wolff about Mr. Trump, his family members, and the Company [the campaign], disclosing Confidential Information to Mr. Wolff, and making disparaging statements and in some cases outright defamatory statements to Mr. Wolff about Mr. Trump, his family members,” Trump attorney Charles Harder wrote in the letter.

The letter, first reported by ABC News, says “remedies for your breach of the agreement include but are not limited to monetary damages.” However, an amount is not disclosed.

In the excerpts published Wednesday, Bannon alleged that Donald Trump Jr.'s meeting with a Russian lawyer in June 2016 was "treasonous" and "unpatriotic," and said Trump’s daughter Ivanka was as “dumb as a brick,” among other things.

Trump fired back.

"Steve Bannon has nothing to do with me or my presidency. When he was fired, he not only lost his job, he lost his mind," Trump said in a statement on Wednesday. "Steve was a staffer who worked for me after I had already won the nomination by defeating seventeen candidates, often described as the most talented field ever assembled in the Republican party."

“Now that he is on his own, Steve is learning that winning isn’t as easy as I make it look,” the statement added. “Steve had very little to do with our historic victory, which was delivered by the forgotten men and women of this country. Yet Steve had everything to do with the loss of a Senate seat in Alabama held for more than thirty years by Republicans. Steve doesn’t represent my base — he’s only in it for himself.”