part of the School of Strategic Studies
Deterrence, in military terms, is the dissuasion of hostile activity by working to make such activity appear unprofitable. This can be obtained by threatening the adversary either to suffer prohibitive costs if he tries to achieve his aims by force (deterrence "by punishment") or to deny him the ability to do so (deterrence "by denial")[1].
The term is most often used since the Second World War in regards to nuclear weaponry, but deterrence as such may also be obtained by other weapons of mass destruction (biological or chemical weapons) or by armies organized for waging conventional war[2]. That is why, following Patrick Morgan (1977, 2003), some scholars have made a distinction between "general deterrence", which rests on dissuading any potential agressor by implicit threats, and "immediate deterrence", backed by explicit conventional and/or nuclear threats.
The chief idea of deterrence by the threat of punishment is to guarantee that, in the event of an engagement in which nuclear devices are employed, the aggressor would be as thoroughly devastated as the conquered party.
Robert Powell, Nuclear Deterrence: The search for Credibility