The official says the classified advice from the Justice's Office of Legal Counsel backs up an unclassified "white paper" from the department that key lawmakers received last year. Several lawmakers have pressed the White House for more information on how decisions are made to target U.S. citizens abroad.
The unclassified memo says it is legal for the government to kill U.S. citizens abroad if it believes they are senior al-Qaida leaders continually engaged in operations aimed at killing Americans.
The official, who was not authorized to discuss the matter publicly, spoke on the condition of anonymity.
