MARINE CORPS AIR STATION YUMA, Ariz. -- U.S. Marine Corps Staff Sgt. Johanny Obregon, the Operations (S-3) Chief with Headquarters and Headquarters Squadron Marine Corps Air Station (MCAS) Yuma, conducts her daily routine duties at MCAS Yuma, Ariz., May 31 2019. In the Marine Corps, S-3 Marines are responsible for the day-to-day training operations that take place on base. (U.S. Marine Corps photo by Pfc. John Hall)