A countermeasure is a system (usually for a military application) designed to prevent weapons from acquiring and/or destroying a target.

It includes the deployment by an ICBM of decoys and chaff in the midcourse phase of flight. For example, a shiny Mylar balloon sheath could hide a warhead among a "threat cloud" with many similar, but empty balloons.

See also

• Electronic countermeasures
• Anti-aircraft
• Anti-ballistic missile