Exercise Vigilant Ace 18: Base Defense
A Republic of Korea defender stands next to a vehicle during their shift change for exercise Vigilant Ace 18 at Osan Air Base, Republic of Korea. During the week-long exercise, the U.S. and ROK are combining their forces, training on mutual support procedures, further improving understanding and trust between the two nations, and ensuring interoperability. (U.S. Air Force photo by Staff Sgt. Alex Fox Echols III)