Unconventional warfare

Unconventional warfare is warfare in a manner differing from that of conventional warfare; in many cases, such unconventional means have been deemed war crimes. Unconventional warfare involves biological weapons, chemical weapons, espionage, genocide, nuclear weapons, special forces, and terrorism. Prior to World War I, the use of military aircraft was often seen as unconventional, and criminal.

See also: asymmetric warfare, low-intensity operations