Intelligence committee Chairwoman Dianne Feinstein halted the hearing and pulled Mr. Brennan from the room until it could be cleared of protesters, who she said were affiliated with Code Pink, the anti-war group.

Mr. Brennan, who is President Obama’s homeland security adviser, is one of the chief architects of U.S. policy in the war on terror, and senators said they are eager to question him about the administration’s program to use drones to execute American citizens deemed to be part of the war on terror overseas.

“Think about the mothers,” cried one female protestor.