President Donald Trump on Wednesday issued a harsh statement on Steve Bannon, his former chief strategist and campaign CEO. The statement came after The Guardian reported on a forthcoming book by journalist Michael Wolff.

The book is Fire and Fury: Inside the Trump White House. It’s based on over 200 interviews with people close to Trump. Bannon, one of those interviewed, is quoted in The Guardian’s report.

In the book, Bannon calls a meeting between Donald Trump Jr., campaign aides and a Russian lawyer “treasonous” and “unpatriotic.” The meeting took place in 2016, after the lawyer promised to deliver incriminating information about Hillary Clinton.

Revelation of the meeting fueled calls for an investigation into Trump’s relationship with Russia. But Trump’s attorney claimed nothing illegal happened.

That’s not how Bannon saw it, apparently. Bannon told Wolff, “even if you thought that this was not treasonous, or unpatriotic, or bad s***, and I happen to think it’s all of that, you should have called the FBI immediately.”

In response, Trump claimed Bannon had “lost his mind.”

JUST IN: Pres. Trump issues statement on former chief strategist Steve Bannon: "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." pic.twitter.com/vn2KeAPIXF

— ABC News (@ABC) January 3, 2018

“Steve Bannon has nothing to do with me or my Presidency,” the statement says. “When he was fired, he not only lost his job, he lost his mind.”

Trump goes on to claim Bannon only worked for him “after I had already won the nomination by defeating seventeen candidates.” His statement suggests Bannon’s reputation as a master mind behind Trump’s success was undeserved.

Continuing, Trump names Bannon as one who repeatedly leaked information from within the White House last year.

“Steve pretends to be at war with the media, which he calls the opposition party,” Trump states. “Yet he spent his time at the White House leaking false information to the media to make himself seem far more important than he was. It is the only thing he does well.”

Trump fired Bannon last August. Bannon then returned to his previous position as executive chairman of Breitbart, a online publication he once called a “platform for the alt-right.” The term has now become a near-synonym for white nationalism. But at the time, Bannon argued it simply indicated a nationalist, not racist, ideology. Bannon maintains that he supports economic nationalism, but rejects ethno-nationalism.

“Steve doesn’t represent my base — he’s only in it for himself,” Trump said Wednesday. He claims Bannon “is simply seeking to burn [the U.S.] down,” rather than “build it up.”