(CBS News) We learned this past week about the administration's legal justifications for the use of drones, that catch-all term for an expanding family of unmanned flying military hardware. The week's revelations further fueled the public debate about the propriety of drone strikes against human targets, and their application within our own border, as we'll hear with Martha Teichner's report in our "Sunday Morning" cover story:
Their names -- Predator, Reaper -- imply their deadly intent. They are what we've come to understand drones to be: Unmanned killing machines armed with hellfire missiles, controlled from thousands of miles away, as they stalk and then destroy supposed terrorist targets in places like Pakistan, Yemen and Afghanistan.
Drones are the controversial weapon of choice in a semi-secret war that was dragged into the spotlight this past week, during confirmation hearings for John Brennan as CIA Director.
Currently the Obama administration's counterterrorism chief, Brennan oversees covert drone strikes.
"The people that were standing up here today, I think they really have a misunderstanding of what we do as a government," said Brennan of protesters. "We only take such actions as a last resort to save lives when there is no alternative taking an action that will mitigate such threat."
But what exactly that means, ethically and even legally, troubles critics. And what we don't know: Estimates cobbled together by journalists and think-tanks of those killed in CIA drone attacks are all over the place.
In Pakistan, since 2004, from under 2,000 at the low end to more than 3,400. The CIA isn't saying. So who's being killed -- terrorists or civilians?
"The data show that only a relatively small number of high-level targets have been killed, something on the order of 50, estimates vary. which is roughly 2 percent of those who have been killed," said James Cavallaro, a law professor at Stanford University. "Which means that 98 percent of those killed have not been high-level targets."
Cavallaro is co-author of a paper critical of U.S. drone use. He and his team went to Pakistan.
"We don't hear enough about the costs, civilians killed, civilians injured, destruction of communities, growth of anti-Americanism, and fomenting recruitment for terrorist groups," he told Teichner. "When all of that is considered, there are serious doubts about whether drones are the best option.
Administration policymakers believe drones often are the best option, for keeping American soldiers out of harm's way.
"This thing that we call war, it's being changed by this technology," said Peter Singer, a senior fellow at the Brookings Institution. "It's allowed us to disconnect two things that used to go hand-in-hand in war: the destructive side, but also the risk of sending people into action. Now you're able to separate them, and that has huge impact."
And here's something you may not know: The vast majority of the 8,000 or so drones in use by the U.S. military more likely look like glorified model airplanes equipped not with missiles but cameras. Together with high-flying surveillance drones, they alert troops when they're in danger.
"In Afghanistan, you have soldiers that will write letters back and say, you know, our patrol was saved today, because you were doing overwatch on us," said Singer.
Now, drones are headed off the battlefield. They're already coming your way.
AeroVironment, the California company that sells the military something like 85 percent of its fleet, is marketing them now to public safety agencies.
Steve Gitlin, a vice-president of AeroVironment, demonstrated for Teicher the company's Qube system: "It's a small unmanned aircraft that's designed to give first responders an immediate eye in the sky so they can find lost kids, they can investigate accidents, they can support disaster recovery for earthquakes in California, tornadoes in the Midwest, hurricanes in the Gulf Coast.
"A Qube system's less than $50,000, which is about what police agencies pay for a fully-equipped police cruiser," Gitlin said.
And much less than what they might pay for a helicopter, which costs $1-2 million a piece.
Suppose you've got a dangerous hostage situation; an unmanned aircraft can track the gunman. It can evaluate flooding, or help firefighters cheaply and safely without endangering lives, the argument goes.
At a North Dakota farm, one assisted in safely resolving an armed standoff over some cattle.
"We were able to tell that there were three adult males at the end of the driveway, which appeared to be holding long guns," said Kelly Janke, Sheriff of Nelson County.
The next morning, the three men were arrested.
"That's when we utilized the UAV again, and we determined that it was safe at the time, and so we moved in, basically, to extract the cattle that we were given a warrant for."