U.S. Marine Corps Lance Cpl. Michael Keller, crewman, Marine Medium Tiltrotor Squadron 265 (Rein), 31st Marine Expeditionary Unit, fires a M2 .50 caliber machinegun at a ground target while participating in a close air support mission during exercise Ssang Yong 2014 on April 1, 2014. Exercise Ssang Yong is conducted annually in the Republic of Korea (ROK) to enhance the interoperability of U.S. and ROK forces by performing a full spectrum of amphibious operations while showcasing sea-based power projection in the Pacific. (U.S. Marine Corps Photo by Lance Cpl. Katelyn Hunter/Released).