Two Northrop Grumman MQ-4C Triton unmanned aerial vehicles are seen on the tarmac at a Northrop Grumman test facility in Palmdale, California May 22, 2013 in this handout photo provided by the U.S. Navy May 22, 2013. Photo taken May 21, 2013. U.S. Navy photo courtesy of Northrop Grumman/Chad Slattery/Handout via Reuters (UNITED STATES - Tags: MILITARY SCIENCE TECHNOLOGY CONFLICT TRANSPORT) 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