Osama bin Laden is shown in this file video frame grab released by the U.S. Pentagon May 7, 2011. Al Qaeda’s leaders were increasingly worried about spies in their midst, drones in the air and secret tracking devices reporting their movements as the U.S.-led war against them grinds on, documents seized in the 2011 raid on Osama bin Laden’s Pakistani hideout and obtained by Reuters reveal. REUTERS/Pentagon/Handout/Files 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.