U.S. Marine Corps Staff Sgt. Michael H. Casey, a section leader with Combat Assault Battalion, III Marine Expeditionary Force, performs maintenance on a Mark 19 grenade launcher March 27, 2014, at Suesongri Range in Pohang, South Korea, during exercise Ssang Yong 2014. Ssang Yong is a combined U.S.-South Korean combat readiness and joint/combined interoperability exercise designed to advance South Korean command and control capabilities through amphibious operations.