Defense secretary Leon Panetta says decisions to strike potential terrorist targets with unmanned drones don't "come lightly".   Panetta says those who authorize the drone strikes make sure they "are focused on somebody who is ... a direct threat to the United States." In an interview released Sunday by NBC, he describes it an "intricate process" of establishing targets, going through legal requirements and trying to limit collateral damage.

Asked about resentment caused by drone strikes, Panetta says the US "has to always pay attention to these issues." But he also says "you've got to use everything you can" against the enemy.

The Pentagon chief says he realized when he became CIA director that he was "making life-and-death decisions." As a Catholic, he says, he's "got to really think about it."