U.S. Marine Sgt. Casey Pena, Marine Air Control Squadron 4 air traffic controller, gives Senior Airman Noah Forsman, 51st Operations Support Squadron air traffic controller, a tour of the mobile operations post at Osan Air Base, Republic of Korea, April 26, 2021. The mobile ops post was set up by the MACS-4 in order to conduct interoperations training with Osan Airmen on mobile air traffic controller techniques. (U.S. Air Force photo by Staff Sgt. Douglas Lorance)