The first U.S. armed drone attack, which appears to be the first such strike ever, took place in mid-November 2001 and killed the military commander of al Qaeda, Mohammed Atef, in Afghanistan.

CNN: A dangerous new world of drones

Earlier this month, the Pentagon said it had received "credible reports" suggesting that Mohammed Atef -- one of al Qaeda's top aides to Osama bin Laden -- was killed in an airstrike south of Kabul.

CNN: Taliban say Omar safe, deny strike hit leadership compound

Perhaps the biggest blow of all suffered by the organisation was last week's death in an American bombing raid in Afghanistan of Mohammed Atef, a relative by marriage of Mr bin Laden, and described in an American court paper as al-Qaeda's military commander.

ECONOMIST: The al-Qaeda network