In the months after the Sept. 11, 2001, attacks, C.I.A. officials were not eager to embrace killing terrorists from afar with video-game controls, said one former intelligence official. “There was also a lot of reluctance at Langley to get into a lethal program like this,” the official said. But officers grew comfortable with the program as they checked off their hit list more than a dozen notorious figures, including Abu Khabab al-Masri, a Qaeda expert on explosives; Rashid Rauf, accused of being the planner of the 2006 trans-Atlantic airliner plot; and Baitullah Mehsud, leader of the Pakistani Taliban.

The drone warfare pioneered by the C.I.A. in Pakistan and the Air Force in Iraq and Afghanistan is the leading edge of a wave of push-button combat that will raise legal, moral and political questions around the world, said P. W. Singer, a scholar at the Brookings Institution and author of the book “Wired for War.”

Forty-four countries have unmanned aircraft for surveillance, Mr. Singer said. So far, only the United States and Israel have used the planes for strikes, but that number will grow.

“We’re talking about a technology that’s not going away,” he said.

There is little doubt that “warheads on foreheads,” in the macho lingo of intelligence officers, have been disruptive to the militants in Pakistan, removing leaders and fighters, slowing movement and sowing dissension as survivors hunt for spies who may be tipping off the Americans. Yet the drones are unpopular with many Pakistanis, who see them as a violation of their country’s sovereignty  one reason the United States refuses to officially acknowledge the attacks. A poll by Gallup Pakistan last summer found only 9 percent of Pakistanis in favor of the attacks and 67 percent against, with a majority ranking the United States as a greater threat to Pakistan than its archrival, India, or the Pakistani Taliban.

Interestingly, residents of the tribal areas where the attacks actually occur, who bitterly resent the militants’ brutal rule, are far less critical of the drones, said Farhat Taj, an anthropologist with the Aryana Institute for Regional Research and Advocacy. A study of 550 professional people living in the tribal areas was conducted late last year by the institute, a Pakistani research group. About half of those interviewed called the drone strikes “accurate,” 6 in 10 said they damaged militant organizations, and almost as many denied they increased anti-Americanism.

Dr. Taj, who lived at the edge of the tribal areas until 2002, said residents would prefer to be protected by the Pakistani Army. “But they feel powerless toward the militants and they see the drones as their liberator,” she said.