A U.S.Marine Corps F-35B joint strike fighter jet conducts aerial maneuvers during aerial refueling training over the Atlantic Ocean in this undated picture released August 20, 2015. The Marine Corps’ F-35B model can take off from warships and aircraft carriers and land like a helicopter. REUTERS/US Marine Corps/Handout THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY. IT IS DISTRIBUTED, EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS. FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS