Donald Trump has revoked the security clearance of his staunch critic, former CIA Director John Brennan, who’s repeatedly called Trump unfit to be president. Brennan served as CIA director under President Obama, where he oversaw the agency’s drone assassination program. Ben Wizner of the ACLU said in response to Brennan’s loss of clearance, “We have been unsparing in our criticism of [John Brennan’s] defense of the CIA torture program and his role in unlawful lethal strikes abroad. But Trump’s revocation of Brennan’s clearance, and his threats to revoke the clearances of other former officials for the sole reason that they have criticized his conduct and policies, amount to unconstitutional retaliation.” At the White House, Press Secretary Sarah Huckabee Sanders said other former executive branch officials who’ve been critical of Trump could be next.

Press Secretary Sarah Huckabee Sanders: “James Clapper, James Comey, Michael Hayden, Sally Yates, Susan Rice, Andrew McCabe, Peter Strzok, Lisa Page and Bruce Ohr. Security clearances for those who still have them may be revoked, and those who have already lost their security clearance may not be able to have it reinstated.”

Among former administration officials whose security clearance the White House isn’t reviewing: Michael Flynn, Trump’s former national security adviser who pleaded guilty to lying to the FBI over his conversations with Russian officials.