Spc. Brandon Brooks, assigned to B Troop, 1st Squadron

Spc. Brandon Brooks, assigned to B Troop, 1st Squadron (Airborne), 40th Cavalry Regiment, 4th Brigade Combat Team (Airborne), 25th Infantry Division, U.S. Army Alaska, conducts chemical, biological, radiological and nuclear defense training on Joint Base Elmendorf-Richardson, Alaska, Wednesday, April 13, 2016. The training culminated with masked Soldiers entering a sealed chamber filled with CS, then removing their protective gear to promote confidence in their equipment. CS, technically known as 0 chlorobenzalmalononitrile, is a solid white powder mixed with a dispersal agent and commonly referred to as tear gas. (U.S. Air Force photo/Justin Connaher)