Electronic warfare (EW) refers to any action involving the use of the electromagnetic spectrum or directed energy to control the spectrum or to attack the enemy. The purpose of electronic warfare is to deny the opponent the advantage of, and ensure friendly unimpeded access to, the EM spectrum. EW can be applied from air, sea, land, and space by manned and unmanned systems, and can target communication, radar, or other services.<ref>Joint Publication 3-13.1 Electronic Warfare</ref> EW includes three major subdivisions: Electronic Attack (EA), Electronic Protection (EP), and Electronic warfare Support (ES).
== Divisions == === Electronic support === Electronic Warfare Support (ES), is the subdivision of EW involving actions tasked by, or under direct control of, an operational commander to search for, intercept, identify, and locate or localize sources of intentional and unintentional radiated Electromagnetic (EM) energy for the purpose of immediate threat recognition, targeting, planning, and conduct of future operations. <ref>Joint Publication 3-13.1 Electronic Warfare</ref>
An overlapping discipline, Signals Intelligence (SIGINT) is the related process of analyzing and identifying the intercepted frequencies (e.g. as a cell phone or RADAR). SIGINT is broken into three categories: ELINT, COMINT, and FISINT.
Where these activities are under the control of an operational commander and being applied for the purpose of situational awareness, threat recognition, or EM targeting, they also serve the purpose of Electronic Warfare Support (ES).
=== Electronic attack ===
Main article: Electronic countermeasures Electronic attack (EA) or electronic countermeasures (ECM) involves the use of the electromagnetic energy, or anti-radiation weapons to attack personnel, facilities, or equipment with the intent of degrading, neutralizing, or destroying enemy combat capability and is considered a form of fires (see Joint Publication [JP] 3-09, Joint Fire Support). <ref>Joint Publication 3-13.1 Electronic Warfare</ref>
EA operations can be detected by an adversary due to their active transmissions. Many modern EA techniques are considered to be highly classified. Examples of EA include communcations jamming, IADS suppression, DE/LASER attack, expendable decoys (e.g., flares and chaff), and counter radio controlled improvised explosive device (C-RCIED) systems.
=== Electronic protection ===
Main article: Electronic counter-countermeasures Electronic Protection (EP) (also known as electronic protective measures (EPM) or electronic counter countermeasures (ECCM)) involves actions taken to protect personnel, facilities, and equipment from any effects of friendly or enemy use of the electromagnetic spectrum that degrade, neutralize, or destroy friendly combat capability. EP should not be confused with self-protection (jamming).
The use of flare rejection logic on an IR missile to counter an adversary’s use of flares is EP. While defensive EA actions and EP both protect personnel, facilities, capabilities, and equipment, EP protects from the EFFECTS of EA (friendly and/or adversary). Other examples of EP include spread-spectrum technologies, use of Joint Restricted Frequency List (JRFL), emissions control (EMCON), and low observability or "stealth". <ref>Joint Publication 3-13.1 Electronic Warfare</ref>