This account of what led to the [Anwar al-]Awlaki strike, based on interviews with three dozen current and former legal and counterterrorism officials and outside experts, fills in new details of the legal, intelligence and military challenges faced by the Obama administration in what proved to be a landmark episode in American history and law.
One morning in late September 2011, a group of American drones took off from an airstrip the C.I.A. had built in the remote southern expanse of Saudi Arabia. The drones crossed the border into Yemen, and were soon hovering over a group of trucks clustered in a desert patch of Jawf Province, a region of the impoverished country once renowned for breeding Arabian horses.
A group of men who had just finished breakfast scrambled to get to their trucks. One was Anwar al-Awlaki, the firebrand preacher, born in New Mexico, who had evolved from a peddler of Internet hatred to a senior operative in Al Qaeda's branch in Yemen. Another was Samir Khan, another American citizen who had moved to Yemen from North Carolina and was the creative force behind Inspire, the militant group's English-language Internet magazine.
Two of the Predator drones pointed lasers on the trucks to pinpoint the targets, while the larger Reapers took aim. The Reaper pilots, operating their planes from thousands of miles away, readied for the missile shots, and fired.