U.S. Air Force Senior Airman Steve Zeckser, a crew chief with the 379th Expeditionary Aircraft Maintenance Squadron, monitors the refueling of a KC-135 Stratotanker at Al Udeid Air Base, Qatar, Jan. 23, 2018. The KC-135 is assigned to the 340th Expeditionary Air Refueling Squadron that is responsible for delivering two-thirds of all fuel to airborne receivers in the U.S. Central Command’s area of responsibility. (U.S. Air National Guard photo by Master Sgt. Phil Speck)