CAPITOL HILL — President Barack Obama’s pick for CIA director says U.S. drone strikes are carried out judiciously and in compliance with federal law.

The Senate Select Committee on Intelligence questioned counter-terrorism adviser John Brennan days after an administration memo surfaced that provided a legal justification for drone strikes targeting U.S. terror suspects abroad.

U.S. drones have killed scores of suspected terrorists in faraway lands. But in approving strikes against a U.S. citizen, Democratic Senator Ron Wyden fears President Obama could be acting as judge, jury and executioner.

“It is the idea of giving any president unfettered power to kill an American without checks and balances that is so troubling,” said Wyden. “Every American has the right to know when their government believes it is allowed to kill them.”

Testifying at his confirmation hearing, CIA director nominee John Brennan defended the drone program.

“We only take such actions as a last resort to save lives when there is no other alternative to taking an action that is going to mitigate that threat,” said Brennan.

The hearing was interrupted by protesters condemning the deaths of innocent bystanders in drone strikes.

Brennan said the American public is misinformed about the drone program, adding that the CIA prefers to capture terrorists.

“I never believe it is better to kill a terrorist than to detain him,” he said. “We want to detain as many terrorists as possible so we can elicit intelligence from them in an appropriate manner and disrupt terrorist attacks.”

As for the treatment of detainees, Brennan said waterboarding is “reprehensible”.

“It is something that should have been banned long ago. It never should have taken place, in my view,” he said.

Drones are low-cost, lethal machines, according to Georgetown University national security expert Christopher Swift.

“From a purely counter-terrorism operations standpoint, drones have proven to be extremely effective in Pakistan and in Yemen,” said Swift.

But their use comes at a price: they fan local anti-U.S. sentiment.

“To the extent that our use of force in somebody else’s country creates political resentment, or feeds into concerns about colonialism or American imperialism, or to the extent that it reinforces this notion that the United States is at war with Islam, it is highly problematic for us,” he said.

If confirmed, Brennan would follow David Petraeus, who resigned as CIA director after an extramarital affair came to light.