Civil liberties groups have been pressuring the administration to offer justification for what has been described as a top-secret „targeted kill“ program in which Americans who have joined al Qaeda or other militants are deemed legitimate targets to be killed overseas.

U.S. Attorney General Eric Holder plans to address the issue and the underpinning legal principles for using lethal force during remarks at Northwestern University School of Law on Monday afternoon in Chicago, the source said Sunday on condition of anonymity.