Members from the 51st Security Forces Squadron survey an area that was damaged by a mortar during exercise Vigilant Ace 18 at Osan Air Base, Republic of Korea. There was a simulated mortar attack that damaged a fuel truck and caused one simulated fatality. U.S. and RoK forces train and conduct exercises together that are focused on full-spectrum operations to deter, and if necessary defeat, a rapidly evolving threat. (U.S. Air Force photo by Staff Sgt. Franklin R. Ramos/Released)