When American and allied forces pushed into the Taliban stronghold of Marja, in southern Afghanistan, last week, they had the advantage of knowing where dozens of roadside bombs had already been planted. And when some troops came under fire, they called in help from a weapon that has quietly become one of the military’s most versatile tools on the Afghan battlefield: the drone.

The use of the drones has expanded quickly and virtually unnoticed in Afghanistan. The Air Force now flies at least 20 Predator drones  twice as many as a year ago  over vast stretches of hostile Afghan territory each day.

They are mostly used for surveillance, but have also carried out more than 200 missile and bomb strikes over the last year, including 14 strikes near Marja in the last few days, newly released military records show. That is three times as many strikes in the past year as in Pakistan, where the drones have gotten far more attention and proved more controversial for their use in a country where the United States does not have combat forces.

There, they are run by the C.I.A., as opposed to the military, and the civilian casualties that they have caused as they have struck at leaders of Al Qaeda and the Taliban, amid Pakistani sensitivities over sovereignty, have stoked anger and anti-Americanism.