electronic warfare (idea)

The part of warfare that deals with use of electromagnetic spectrum to harm the enemy or protect friendly units from such attacks.

This includes, among other things:

• electronic countermeasures (ECM) and electronic counter-countermeasures
• electronic attacks, used to disrupt enemy's use of electromagnetic things, or used to cause damage using electromagnetic devices
• electronic protection, used to protect things from electromagnetic attacs
• electronic warfare support that provides information about use of electronic attacks and defenses (for threat recognition, for example).

(summarized, to the extent I could understand of this stuff, from "Space & Electronic Warfare Lexicon", http://www.saw-lexicon.com/)