The CIA's Silent War in Pakistan

Moreover, while the drones may seem a technological marvel and strategic asset to those waging the campaign on the American side, they don't impress the local tribesmen. On the contrary, they feed a perception that the U.S. is a cowardly enemy, too frightened to shed blood in battle. "The militants say that if the Americans want to come and fight, they should fight them face to face," says Mahmood Shah, a retired brigadier who was once the top Pakistani official in FATA. Shah, a Pashtun himself, says the families of the drones' victims are required under the tribal code to seek revenge, which makes them ideal recruits for militant leaders like Baitullah Mehsud, the Pashtun commander of the Pakistani Taliban. Mehsud, says Shah, "likes to boast that each drone attack brings him three or four suicide bombers."

Cheap and Deadly

The Predator and the Reaper are both made by General Atomics, a San Diego defense contractor. The Predator is the older of the two; the first one was delivered to the Air Force in 1994. By the end of the 1990s, the CIA was using it to track bin Laden. Capable of flying for up to 40 hours without refueling, the drone was a "brilliant intelligence tool," recalls Hank Crumpton, then the CIA's top covert-operations man in Afghanistan. Although the CIA was keen to weaponize the drone early on, the Air Force resisted the idea until 2000. Even then, firing the weapons was another matter. Crumpton remembers watching someone he is convinced was bin Laden on a video feed from a Predator in late 2000. "The optics were not great, but it was him," Crumpton says. But back then, "there were too many political, legal and military constraints," and the CIA couldn't simply pull the trigger. The equation changed after 9/11. The Predator drew blood for the first time on Nov. 5, 2002, when it destroyed an SUV in Yemen, killing six men, including a top local al-Qaeda leader. (See a diagram of a Reaper here.)

The Predator's firepower is limited, but the Reaper can deliver laser-guided 500-lb. bombs like those commonly found on the F-16 jet, together with Hellfire missiles. And the hardware comes relatively cheap. The Reaper costs $10 million--chump change compared with manned fighter aircraft; the cutting-edge F-22 Raptor, for instance, costs nearly $350 million. The drones' relatively low cost is due mainly to the fact that they don't have a pilot--which may also contribute to the Pakistani leadership's tacit acceptance of the CIA campaign. "If we were sending F-16s into FATA--American pilots in Pakistani airspace--they might have felt very differently," says James Currie, a military historian at the U.S.'s National Defense University.

By staring at hours of video footage of houses, vehicles and people, analysts looking at screens in Nevada can detect "patterns of life analyses," or timelines of movements and meetings in any given area. But the drones' utility is dramatically enhanced when analysts know exactly what they're looking for and where. For that, there's nothing better than human intelligence. Reports from Waziristan suggest the CIA has access to a network of spies. Tribesmen have told TIME of agents who drop microchips (locally known as patrai) near targets; the drones can lock onto these to guide their missiles or bombs with pinpoint precision. But it has proved difficult to verify these claims of human assets and their homing chips.