U.S. sailors use an aircraft tow tractor to move an AH-1Z Viper helicopter on the port side elevator aboard the amphibious assault ship USS Peleliu (LHA 5) under way in the Pacific Ocean May 31, 2012. Peleliu and her amphibious ready group are participating in a combined amphibious squadron and U.S. Marine Corps Marine expeditionary unit integrated training. (U.S. Navy photo by Mass Communication Specialist Seaman Derek Stroop/Released)