Electronic warfare (EW) is the use of the electromagnetic spectrum to deny its effective use by an adversary.
Electronic warfare has three main components:
* Electronic Attack (EA)
This is the active or passive use of the electromagnetic spectrum to deny its use by an adversary.
An older term for EA is electronic countermeasures (ECM).
Active EA includes such activities as jamming, deception, active cancellation and EMP use.
Passive EA includes such activities as the use of chaff, towed decoys, balloons, radar reflectors, propelled and unpropelled winged decoys and stealth.
Many modern EA techniques are considered to be highly classified.
* Electronic Protection (EP)
This includes all activities related to making enemy EA activities less successful by means of protecting friendly personnel, facilities, equipment or objectives. EP can also be implemented to prevent friendly forces from being affected by their own EA.
Older terms for EP are electronic protective measures (EPM) and electronic counter countermeasures (ECCM).
Active EP includes such activities as technical modifications to radio equipment (such as frequency-hopping spread spectrum).
Passive EP includes such activities as education of operators (enforcing strict discipline) and modified battlefield tactics or operations.
* Electronic Support (ES)
This is the passive use of the electromagnetic spectrum to gain intelligence about other parties on the battlefield in order to find, identify, locate and intercept potential threats or targets.
An older term for ES is electronic support measures (ESM).
This intelligence might be used directly as fire missions for artillery or air strike orders, for mobilization of friendly forces to a specific location or objective on the battlefield or as the basis of EA/EP actions.
EA operations can be detected by an adversary due to their active transmissions. ES, however, can be conducted without the enemy ever knowing it. Its counterpart, SIGINT, is continuously performed by most of the world's countries in order to gain intelligence derived from other parties' electronic equipment and tactics.