Al Qaeda's founders remain elusive. U.S. spy agencies have not had reliable intelligence on the location of Osama bin Laden since he slipped across the Pakistan border seven years ago, officials said. His deputy, Ayman Zawahiri, remains at large after escaping a missile strike in 2006.
But the Predator campaign has depleted the organization's operational tier. Many of the dead are longtime loyalists who had worked alongside Bin Laden and were part of the network's hasty migration into Pakistan in 2001 after U.S.-led forces invaded neighboring Afghanistan. They are being replaced by less experienced recruits who have had little, if any, history with Bin Laden and Zawahiri.
The offensive has been aided by technological advances and an expansion of the CIA's Predator fleet. The drones take off and land at military airstrips in Pakistan, but are operated by CIA pilots in the United States. Some of the pilots -- who also pull the triggers on missiles -- are contractors hired by the agency, former officials said.
Predators were originally designed as video surveillance aircraft that could hover over a target from high altitudes. But new models are outfitted with additional intelligence gear that has enabled the CIA to confirm the identities of targets even when they are inside buildings and can't be seen through the Predator's lens.
The agency is also working more closely with U.S. special operations teams and military intelligence aircraft that hug the Pakistan border, collecting pictures and intercepting radio or cellphone signals.
Even so, officials said that the surge in strikes has less to do with expanded capabilities than with the decision to skip Pakistani approval. "We had the data all along," said a former CIA official who oversaw Predator operations in Pakistan. "Finally we took off the gloves."
The Bush administration's decision to expand the Predator program was driven by growing alarm over Al Qaeda's resurgence in Pakistan's tribal belt.
A 2006 peace agreement between Islamabad and border tribes had allowed the network to shore up its finances, resume training operatives and reestablish connections with satellite groups.
The Bush administration had been constrained by its close ties with Pakistani President Pervez Musharraf, who argued against aggressive U.S. action. But by last summer, after a series of disrupted terrorist plots in Europe had been traced to Pakistan, there were calls for a new approach.
