CIA drones are killing terrorists - and civilians - in Pakistan almost every day. The unmanned aircraft are becoming the weapon of choice in the fight against al-Qaeda and its allies. But the political, military and moral consequences are incalculable. Spiegel Online has investigated President Barack Obama's remote-controlled campaign against terrorism.

What is the cost of rendering a terrorist harmless once and for all by killing him? During the course of 14 months, the CIA used unmanned and heavily armed small aircraft known as drones to stage 15 strikes against the presumed locations of the leader of the Pakistani Taliban. On Aug. 5, 2009, on the 16th try, the drones finally managed to kill Baitullah Mehsud.

On that day, a Predator drone was hovering about three kilometers (2 miles) above the house of Mehsud's father-in-law, somewhere in the Pakistani province of South Waziristan. The drone's infrared camera sent remarkably sharp images in real time to CIA headquarters in Langley, Virginia. The images showed the Taliban leader sitting on the roof of his house, in the company of his wife, his uncle and a doctor.

At that very moment, thousands of miles away in the United States, someone pressed a button, and two Hellfire missiles shot from the drone. Mehsud and 11 others were killed.

This incident is so well documented because it was reconstructed for an article in The New Yorker magazine. But the hunt for Mehsud cost the lives of far more than 11 people. According to estimates, between 207 and 321 people died in the course of the 16 attempts to eliminate Mehsud - and it is certain that not all of them were Taliban fighters.