The U.S. government runs two drone programs. The military’s version, which is publicly acknowledged, operates in the recognized war zones of Afghanistan and Iraq, and targets enemies of U.S. troops stationed there. As such, it is an extension of conventional warfare. The C.I.A.’s program is aimed at terror suspects around the world, including in countries where U.S. troops are not based. It was initiated by the Bush Administration and, according to Juan Zarate, a counterterrorism adviser in the Bush White House, Obama has left in place virtually all the key personnel. The program is classified as covert, and the intelligence agency declines to provide any information to the public about where it operates, how it selects targets, who is in charge, or how many people have been killed.