President Trump has revoked the security clearance of former CIA Director John Brennan, a frequent Trump critic. President Trump has revoked the security clearance of former CIA Director John Brennan, a Barack Obama appointee who has criticized Trump over the Russia investigation, White House press secretary Sarah Sanders said in a written statement. Trump also said he continues to review the security clearances of other former Obama-era officials, a list to which he has added names - including officials who have been involved in the investigation of Russia election activity during Trump's election. Sanders said Brennan has engaged in "Erratic behavior" and lodged unfair allegations; Brennan and his supporters said Trump's security review was politically motivated and designed to target his freedom of speech. Ref. USAToday.