Undated handout image courtesy of the U.S. Air Force shows a MQ-1 Predator unmanned aircraft. The U.S. government has authorized the killing of American citizens as part of its controversial drone campaign against al Qaeda even without intelligence that such Americans are actively plotting to attack a U.S. target, according to a Justice Department memo.REUTERS/U.S. Air Force/Lt Col Leslie Pratt/Handout  (UNITED STATES - Tags: CONFLICT POLITICS MILITARY CRIME LAW) FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY. IT IS DISTRIBUTED, EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS
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