Drones Revolutionize US Warfare

They are robots in the sky and some say they are revolutionizing the way the United States wages wars. Drones are playing a growing role in the U.S. military.

It is estimated that there are 10,000 unmanned aerial vehicles in the U.S. military's arsenal, in addition to an undisclosed number operated by the CIA - including one that recently killed Abu Yahya al-Libi, al-Qaida's number two leader.

Pakistan objects to the use of drones over its territory. But U.S. Defense Secretary Leon Panetta has given no indication Washington will stop using them against terrorists.