CBS News has been told that, hours after the attack began, an unmanned Predator drone was sent over the U.S. mission in Benghazi, and that the drone and other reconnaissance aircraft apparently observed the final hours of the protracted battle…

But it was too late to help the Americans in Benghazi. The ambassador and three others were dead.

Retired CIA officer Gary Berntsen believes help could have come much sooner. He commanded CIA counter-terrorism missions targeting Osama bin Laden and led the team that responded after bombings of the U.S. Embassy in East Africa.

“You find a way to make this happen,” Berntsen says. “There isn’t a plan for every single engagement. Sometimes you have to be able to make adjustments. They made zero adjustments in this. They stood and they watched and our people died.”