U.S. Air Force Staff Sgt. Dwight Stalter, 435th Security Forces Squadron contingency response team leader, mounts his rifle to a concrete window during exercise Frozen Defender in Grostenquin, France, Jan. 16, 2020. The exercise was designed to sharpen defenders’ skills when faced with unpredictable circumstances. (U.S. Air Force photo by Staff Sgt. Devin Boyer)