
ALT A U.S. Marine with 26th Marine Expeditionary Unit puts on his gas mask during a simulated chemical attack as a part of a monitoring, surveillance, and decontamination (MSD) course on Marine Corps Base Camp Lejeune, North Carolina, Oct. 21, 2026. The MSD course is designed to train Marines to detect, monitor, survey and decontaminate equipment or personnel during a chemical, biological, radiological or nuclear threat. (U.S. Marine Corps photo by Cpl. Channah Chilton)\n\n

ALT A U.S. Marine with 26th Marine Expeditionary Unit puts on his gas mask during a simulated chemical attack as a part of a monitoring, surveillance, and decontamination (MSD) course on Marine Corps Base Camp Lejeune, North Carolina, Oct. 21, 2026. The MSD course is designed to train Marines to detect, monitor, survey and decontaminate equipment or personnel during a chemical, biological, radiological or nuclear threat. (U.S. Marine Corps photo by Cpl. Channah Chilton)\n\n


























