The author of A Warning is anonymous no more.

Miles Taylor, who served for several months as the chief of staff to the U.S. Secretary of Homeland Security, revealed on Wednesday that he wrote the 2019 book that harshly criticized President Donald Trump, the New York Times reports.

A Warning was published by Hachette imprint Twelve Books, which identified the author only as “a senior Trump administration official.”

“Trump has been exactly what we conservatives always said government should NOT be: expansive, wasteful, arbitrary, unpredictable, and prone to abuses of power,” Taylor wrote in a Medium post on Thursday.

Trump reacted to the revelation by telling the crowd at an Arizona rally that Taylor “should be prosecuted,” as reported by CNN’s Jim Acosta on Twitter. And Sebastian Gorka, an analyst and Trump ally, tweeted that Taylor “should be investigated for sedition.”

Taylor also faced criticism from Chris Cuomo, an anchor at CNN, the network where Taylor now works as a contributor.

“You lied to us, Miles,” Cuomo said. “You were asked in August if you were Anonymous here on CNN with Anderson Cooper and you said no. Now why should CNN keep you on the payroll after lying like that?”

The revelation seems to have given Taylor’s book a sales boost. As of Thursday morning, A Warning was the No. 42 bestselling book at Amazon, and No. 1 in the “Democracy” and “Political Corruption Misconduct” categories.

Michael Schaub is a Texas-based journalist and regular contributor to NPR.