U.S. Air Force Maj. Jacob Johnson, 909th Air Refueling Squadron director of wing inspections and 1st Lt. Huston Harrison, 909th ARS standards and evaluations officer, conduct pre-flight checks aboard a KC-135 Stratotanker April 20, 2017, at Kadena Air Base, Japan. The KC-135 is the Air Force’s primary air refueling capacity. (U.S. Air Force photo by Senior Airman Lynette M. Rolen)