CBRN defense is a (military) collective term for protective and defensive measures against the effects of nuclear, biological and chemical warfare agents. The civilian counterpart is the NBC service.

In the German, Swiss and Austrian armies, the A B C defense force is a separate troop type.

NBC protection refers to protection against nuclear, biological and chemical hazards, including A B C weapons or hazardous material accidents, for example directly by means of A B C protective masks, shelters and bunkers, but also more broadly by sensing endangered and demarcating contaminated areas.

In the German-speaking countries common alternative designations to the acronym “ABC” are:

CBRN (from chemical, biological, radiological and nuclear) as NBC protection with the specification of the classical term “nuclear hazards”: radiological (radioactive, radiating substances) and nuclear (e.g., nuclear weapons, nuclear power plant accidents) incidents,
or CBRNE (CBRN supplemented by explosive substances, in English: “explosives”) for the explicit extension to incidents involving explosives,
and GSG (for Hazardous Substances and Goods), the latter designation excluding nuclear and biological pollutants that are not stored or transported as goods.