Countermeasure

This article is about weapons. For computer security countermeasures, see Countermeasure (computer).

A CH-46 Sea Knight helicopter launches countermeasures (flares and chaff)

Fortification, a passive countermeasure

A countermeasure is a measure or action taken to counter or offset another one. As a general concept it implies precision, and is any technological or tactical solution or system (often for a military application) designed to prevent an undesirable outcome in the process. The first known use of the term is in 1923.

Countermeasures can refer to the following disciplinary spectrum:

• Defense
• Medicine
• Materials engineering
• Electro-magnetic engineering
• Policing
• Information technology
• Law
• Diplomatic security
• Pollution prevention

Defense countermeasures are often subdivided into "active" and "passive" countermeasures.

Active

In military applications, "active" countermeasures which alter the electromagnetic, acoustic or other signature(s) of a target thereby altering the tracking and sensing behavior of an incoming threat (e.g., guided missile) are designated soft-kill measures. Measures that physically counterattack an incoming threat thereby destroying/altering its payload/warhead in such a way that the intended effect on the target is severely impeded, such as close-in weapon systems, are designated hard-kill measures. Both types are further described in active protection systems.

Passive

"Passive" countermeasures include:

• Armor
• Camouflage
• Fortification
• Self-sealing fuel tank

See also

• Anti-aircraft
• Anti-ballistic missile
• Electronic countermeasures
• Flare (countermeasure)
• Infrared countermeasures
• Mine countermeasures
• National Missile Defense
• Self-defense
• Strategic Defense Initiative
• Tactic (method)