A U.S. Air Force petroleum, lubricants and oil Airman observes fuel-loading equipment during Exercise Mobility Guardian 2021 at Oscoda-Wurtsmith Airport, Oscoda, Michigan, May 18, 2021. Exercises like Mobility Guardian prepare Mobility Airmen to face real-world security challenges and sustain strategic deterrence anywhere, anytime. (U.S. Air Force photo by Senior Airman Lawrence Sena)