President Donald Trump yanked the White House security clearance for former CIA Director John Brennan on Wednesday, and he could target others critical of him next.

The move was announced by press secretary Sarah Huckabee Sanders, who cited “the risk posed by his erratic conduct and behavior.”

Brennan, CIA chief from 2013-17, has been vocal about his disdain for Trump on the president’s most-used social media platform, tweeting Tuesday that he would “never understand what it means to be president, nor what it takes to be a good, decent & honest person. So disheartening, so dangerous for our nation.” He echoed those comments in an MSNBC appearance Tuesday night.

The comments were in response to Trump attacking former White House aide Omarosa Manigault Newman by calling her “that dog” after she began to leak a series of taped conversations to the press. But Brennan’s verified account has been pretty much tweeting only about Trump over the past several months, often criticizing him for attacking the Russia investigation.

Dan Coats, director of national intelligence, wasn’t consulted before Trump’s move to revoke, according to CNN. In July, when the president's team first indicated that he might begin to pull security clearances from former national security and intelligence officials, Speaker of the House Rep. Paul Ryan said he thought Trump was “trolling people, honestly.” At the time, Jeffrey Smith, former general counsel for the CIA, told PBS that such a move had “never happened before, not even in the McCarthy or Nixon era.” And former FBI Special Agent Frank Montoya told CNN in July that it would be “absolutely unprecedented” and “an abuse of power,” although the president is the final authority on security clearances.

After national security and intelligence officials exit an administration, they often keep their access so they can provide necessary counsel. Analysts say it's important for any administration to be able to quickly access the expertise of former officials in case of national emergencies. Trump is also reviewing the security clearances of other former officials, including former FBI Director James Comey, the Washington Post reported. Comey apparently no longer has his security clearance anyway. The White House is also considering revoking security clearances from former director of National Intelligence James Clapper, former acting Attorney General Sally Yates, and former National Security Adviser Susan Rice, among others.