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
"Active" countermeasures 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 majorly impeded are designated hard-kill measures. Both are further described in active protection systems.

Passive
"Passive" countermeasures include:
 * Armor
 * Camouflage
 * Fortification
 * Self-sealing fuel tank