US president Barack Obama's use of unmanned drones to kill Americans who are suspected of being al-Qa'ida allies deserves closer inspection, US lawmakers have said, as even some of the president's allies suggested uneasiness about the programme.
"We are in a different kind of war. We're not sending troops. We're not sending manned bombers. We're dealing with the enemy where we find them to keep America safe.
"We have to strike a new constitutional balance with the challenges we face today," said Senator Dick Durbin.
"The policy is really unfolding. Most of this has not been disclosed," he added.
Before John Brennan's confirmation hearing to lead the CIA on Thursday, Mr Obama directed the Justice Department to give the congressional intelligence committees access to classified legal advice providing the government's rationale for drone strikes against US citizens working with al-Qa'ida.
Former Defence Secretary Bob Gates, a former CIA chief, suggested "some check" on a president's ability to order drone strikes against American al-Qa'ida operatives would be appropriate and lent support to creating a special court that would review such requests.
The potential model that some lawmakers are considering for overseeing such drone attacks is a secret court of federal judges that now reviews requests for government surveillance in espionage and terrorism cases.