Chemical, biological, radiological and nuclear defense (CBRN defense or CBRNE defense) is protective measures taken in situations in which chemical, biological, radiological or nuclear warfare (including terrorism) hazards may be present. CBRN defense consists of CBRN passive protection, contamination avoidance and CBRN mitigation.
A CBRN incident differs from a hazardous material incident in both scope (i.e., CBRN can be a mass casualty situation) and intent. CBRN incidents are responded to under the assumption that they are intentional and malicious; evidence preservation and perpetrator apprehension are of greater concern than with HAZMAT incidents.
In English the term CBRN is a replacement for the cold war term NBC (nuclear, biological, and chemical), which had replaced the term ABC (atomic, biological, and chemical) that was used in the fifties. The addition of the R (for radiological) is a consequence of the "new" threat of a radiological weapon (also known as "dirty bombs"). In the new millennium, the term CBRNe was introduced as an extension of CBRN - the e in this term representing the enhanced (improvised) explosives threat. 
In Spanish the term NRBQ (Nuclear, Radiológico, Bacteriológico y Químico) has replaced NBQ.
By country or region
The Argentine Armed Forces has the Batallón de Ingenieros QBN 601 of the Argentine Army, was the first CRBN response team created, in the 1990s, as a part of the country's Rapid Deployment Force. The Policía Federal Argentina have the BRIGADA DE RIESGOS ESPECIALES (BRE), this unit is the only national response for CBRN/HAZMAT incidents. Also, has a three units called: RIESGO QUIMICO Y BIOLOGICO, RIESGO RADIOLOGICO Y NUCLEAR, and the tactical response unit called PROTECCION QBNR.
Brazilian firefighters are trained for NBC situations. Due to the 2016 Summer Olympics, police forces, like the GATE from Minas Gerais, the Federal Police and the National Public Security Force, are being prepared too. 
In the military area, there is CBRN equipment and personnel by all the Armed Forces. The Brazilian Army has two specific teams: the 1st Chemical, Biological, Radiological and Nuclear Defense Battalion, which is based at Rio de Janeiro and is responsible by decontaminating military equipment, weapon and personnel,  and the Chemical, Biological, Radiological and Nuclear Defense Company, based at Goiânia and part of the Brazilian Special Operations Command, that makes the decontamination and defense in CBRN situations.  The Brazilian Presidential Guard and Army Police also have CBRN units.  
The Brazilian Marine Corps has the CDefNBQR (Nuclear, Biological, Chemical and Radiological Defense Center)    that controls the ARAMAR Nuclear, Biological, Chemical and Radiological Defense Battalion, at Iperó, São Paulo, conceived to provide the physical security and to perform CBRN emergencies control actions at the Centro Experimental Aramar, responsible for developing Brazilian Navy nuclear researches;  the Itaguaí Nuclear, Biological, Chemical and Radiological Defense Battalion, at Itaguaí, Rio de Janeiro, where it's going to be hosted the first Brazilian Navy nuclear-powered submarine; and the Nuclear, Biological, Chemical and Radiological Defense Company, at Duque de Caxias, Rio de Janeiro.  The Air Force is making special teams for transporting victims from CBRN attacks/accidents. 
The term CBRN is in common use in disaster and emergency services organizations across the country.  Since July 2005, the Canadian Armed Forces also started using the term CBRN Defence, instead of NBC Defence, due to the increased threat of dirty bomb use (which is radiological in nature). CBRNE is a new term that is being used in both civilian and military organisations. The Canadian Joint Incident Response Unit is a Canadian Forces unit, under the direction of the Canadian Special Operations Forces Command, charged with supporting "the Government of Canada in order to prevent, control and mitigate CBRN threats to Canada, Canadians and Canadian interests."
All members of the Canadian Armed Forces are trained in CBRN defense, and maintain minimum standards tested at a minimum, every three years.
At the provincial level, cities are provided opportunities for their emergency services with CBRN training. In Ontario, emergency services in Windsor, Peterborough, Toronto, and Ottawa have obtained CBRN standing at NFPA Standard 472 Awareness Level 3. 
In mid-July 2016, the European Parliament negotiated a new draft counterterrorism directive aimed at protecting Europe's people from biological, chemical and other attacks. The timeline of the directive is illustrated in the following table: 
|Date or target date||Action|
|4 July 2016||The European Parliament’s Civil Liberties, Justice and Home Affairs Committee approved amendments to its directive counter-terrorism.|
|14 July 2016||Negotiations began. Monika Hohlmeier, the chief negotiator for the European Parliament, is charged with negotiating the final text of the directive with the European Council (heads of state for all 28 European Union countries). The European Commission will serve as a facilitator in the negotiations.|
|Fall 2016||Negotiations expected to be concluded.|
The directive would criminalize: 
- Certain acts related to preparing for a terrorist attack, such as traveling abroad to meet with a terrorist group
- Training to make explosives, firearms, and other dangerous substances
- Public incitement or praise for terrorism and financing of terrorism
The directive also includes text to help victims of terror attacks. 
Hong Kong has had CBRN response capabilities since the early 1990s and advanced training from 1998.  The Standing CBRN Planning Group (known as the SRPG) plans for all CBRN incidents in Hong Kong. The SRPG was set up with the support of the Secretary for Security by the Senior Bomb Disposal Officer in Hong Kong, Dominic Brittain.  It consists of representatives from 9 government departments who plan the response to CBRN threats. These departments include Police EOD, Fire Services, the Hospital Authority and the Department of Health, amongst others.The operational arm of the SRPG is the CBRN Incident Advisory Group (RIAG) who form up in the initial stages of a CBRN incident using telephone conferencing. RIAG consists of five experts who assist with the technical response to the incident by providing real time advice and support to the departments involved. The Hong Kong capability is well rehearsed, with regular departmental exercises conducted and a full scale CBRN exercise conducted every year. 
The Indian Army ordered 16 CBRN monitoring vehicles, of which the first 8 were inducted in December 2010. It was developed by the Defence Research and Development Organisation (DRDO) and manufactured by Ordnance Factories Board. 
The Indonesian Army has a CBRN Defense unit, Kompi Zeni Nubika Ditzi TNI-AD. The unit was founded on 22 April 1986 under the command of Indonesian Army Engineering Directorate. The unit also corporated with Ministry of Health, Indonesian Nuclear power regulator agency, Verteliner Research Agency, and National Nuclear Power agency. This unit is the one and only unit that can handle CBRN Defense Capability. 
Ireland (Republic of)
The Irish Defence Forces have CBRNE training and equipment capabilities – in particular the Ordnance Corps (Explosive Ordnance Disposal/EOD teams), Engineer Corps and Army Ranger Wing (ARW) – and will aid the civil authority if requested. The Irish Army runs CBRNE defence courses, and has detection equipment, decontamination equipment and is reported to have purchased 10,000 protective CBRN/NBC suits, enough for all of its personnel.  All Army Reserve personnel undergo CBRN warfare defence training. 
The Irish national police force, the Garda Síochána, has a number of nationwide CBRN response teams. The teams are based regionally (in six regions; Dublin, Eastern, Northern, Southern, South-Eastern & Western) and began operating from 2004 with 100 trained officers (170 responders trained throughout the country as of 2009). There is a requirement for members to be re-certified within 18 months of training.   CBRN response teams are trained by the Garda Tactical Training Unit, and supported nationally by the Emergency Response Unit (ERU).  Other emergency services also have limited CBRN expertise, such as the Health Service Executive (HSE) and Dublin Fire Brigade (DFB), who have a Hazardous Materials (Haz-Mat) and Chemical Incident Unit.
The Royal Malaysia Police has CBRN providers. The Pasukan Gerakan Khas (PGK) has two special operations detachments with HAZMAT expertise - 69 Commandos and Special Actions Unit. The Federal Reserve Unit (FRU) also has a CBRN unit. Both PGK and FRU teams handle CBRN calls, before an army PNBK unit responds. 
The Spanish Army 1st CBRN Regiment 'Valencia' was formed in March 2005.Training in the defence against CBRN agents as part of combat support is the main aim of exercise 'Grifo' (Griffin) – the most important of this type that the Army undertakes. The National Police and the Spanish Civil Guard have their own CBRN units. The Military Emergencies Unit and emergency services have CBRN training.  
CBRN is also used by the UK Home Office as a civil designation.  Police, fire and ambulance services in the UK must all have some level of CBRN providers. Within the ambulance service this is performed by the Hazardous Area Response Team (HART) and Special Operations Response Team (SORT). Since the introduction of new equipment to UK fire services under the New Dimension programme, CBRN decontamination of personnel (including members of the public) has become a task carried out by fire services in the UK and they regularly train for such scenarios.
The United States Army uses CBRN as an abbreviation for their Chemical, Biological, Radiological, and Nuclear Operations Specialists (MOS). The United States Army trains all US Army soldiers pursuing a career in CBRN at the United States Army CBRN School (USACBRNS) at Fort Leonard Wood.
The USAF uses Air Force Specialty Code (AFSC 3E9X1) U.S. Air Force Emergency Management, who are also CBRN Specialists. The USAF trains all US Airmen pursuing a career in counter-CBRN operations at the USAF CBRN School at Fort Leonard Wood.
The USMC uses CBRN as an abbreviation for two military occupational specialties. The Marine Corps runs a CBRN School to train Marine CBRN Defense Officers and Marine CBRN Defense Specialists at Fort Leonard Wood, Missouri. See also: Chemical Biological Incident Response Force (USMC CBIRF)
The USN requires all personnel to take a web-based CBRNE training annually to get a basic understanding of facts and procedures related to responding to a CBRNE incident.
The Russian Federation
The Radiation, Chemical and Biological Protection Troops (RChBP Troops) of the Russian Federation are special forces designed to conduct the most complex set of measures aimed at reducing the loss of associations and formations of the Ground Forces and ensuring their combat tasks assigned during operations in conditions of radioactive, chemical and biological contamination, as well as at enhancing their survivability and protection against high-precision and other weapons. 
The Russian government vaccinated around half a million reindeer against anthrax in 2015.  Around 1.5 million reindeer carcasses in Russian permafrost are at risk of melting due to global warming in the Arctic.  There is a risk that global warming in the Arctic can thaw the permafrost, leading to new infections in reindeer. An anthrax outbreak in 2016 in reindeer caused the Russian Armed Forces to evacuate a nomadic reindeer herding tribe.
In May 2012, BioPrepWatch reported that the Russian security service ordered over 100 "capsule cradles", which are devices that people can use to protect infants or even small pets in the event of a nuclear, chemical, biological, or radiological threat. According to the article, Soviet military engineers invented the capsules in the 1960s. A company is currently producing the capsules in a factory in Russia. 
Numbers vary, but news reports and market forecast reports place the market for CRBN products in 2013 and 2014 between $8.7–8.8 billion.   The market for CBRN products is expected to grow to over $13 billion by the year 2023.  CBRN manufacturers include Ansell, Argon Electronics, Blucher GmbH, Bruker, FLIR Systems, I-SKYEX, HDT Global, MSA, Ouvry, Research International, and TSI.
- Ansell is a manufacturer of personal protective equipment, who carry a range of gas- and liquid-tight suits.
- Argon Electronics makes a CBRN detection simulator that personnel can use in training exercises. 
- Blucher GmbH produces a two-piece CBRN protective suit that gives first responders 24-hour protection against environmental threats. 
- Bruker produces ion-mobility spectrometry for military and security personnel that separates, identifies and analyzes ionized molecules present in gas. 
- FLIR Systems produces several handheld detection equipment devices, each for chemical, radiation, biological and explosives detection. 
- HDT Global produces an air filtration system that government forces can install in buildings, ships and vehicles to remove CBRN threats from the air. 
- I-SKYEX produces unmanned aerial systems (UAS) as a response to CBRN threats or incidents. 
- MSA produces respirators, with a hood that filters CBRN particles for use by personnel responding to a terrorist incident. 
- Ouvry develops and manufactures CBRN personal protective equipment (PPE). 
- Research International creates a sensor system, for subways and other public areas that uses multi-sensor surveillance technology that detects the presence of CBRN particles. 
- TSI makes a product that collects CBRN environmental samples to identify and confirm threats.