U.S. Air Force Airmen with Air Education and Training Command, compete in a dismounted operation competion during Air Force Defender Challenge Sept. 12, 2018 at Joint Base San Antonio-Camp Bullis, Texas. During the challenge Airmen are placed into a four-person team and move as quickly as possible across a 3-6 mile distance while using teamwork to overcome physical and mental barriers. (U.S. Air Force photo by Sarayuth Pinthong)