The Obama administration’s legal rationale for assassinating U.S. citizens without charge has been revealed for the first time. A secret Justice Department document obtained by NBC News says the administration can target citizens who are “senior operational leaders” of al-Qaeda or “an associated force” — even if there is no intelligence indicating they’re engaged in an active plot to attack the United States. The document is described as a “white memo” provided to members of the Senate Intelligence and Judiciary Committees last year. Its release follows a series of failed efforts by civil liberties groups to obtain the government’s legal justification for the targeted killing of an American.