A U.S. Marine with the 26th Marine Expeditionary Unit equips his gas mask during a chemical, biological, radiological and nuclear (CBRN) training event at Camp Lejeune, N.C., Dec. 18, 2017.
The training provided Marines with a basic knowledge of how to effectively utilize their equipment and to defend against CBRN attacks. (U.S Marine Corps photo by Cpl Austin M. Livingston) Original public domain image from Flickr