U.S. Marines assigned to Marine Wing Support Squadron (MWSS) 274, conduct Chemical Biological Radiological and Nuclear Training as part of the Air Base Ground Defense (ABGD) Field Exercise at Marine Auxiliary Landing Field Bogue, N.C.

CBRN is an initialism used to refer to chemical, biological, radiological and nuclear warfare. Chemical, biological, radiological and nuclear defense (often abbreviated to CBRN defense or CBRND) is the term for protective measures taken in situations in which any of these four hazards are present. To account for improvised devices, the term CBRNe (e for explosives) is also used. CBRN defense consists of CBRN passive protection, contamination avoidance and CBRN mitigation.

CBRN weapons or agents are often referred to as weapons of mass destruction (WMD). However, this is not entirely correct. Although CBRNe agents often cause mass destruction, this is not necessarily the case. Terrorist use of CBRNe agents may cause a limited number of casualties, but a large terrorizing and disruption of society. Terrorist use of CBRNe agents, intended to cause terror instead of mass casualties, is therefore often referred to as weapons of mass disruption.