The success of deterrence depends on the credibility of the retaliatory threat and on the rationality of the opponent. Opponents must truly believe that their actions will result in retaliatory responses that inflict unacceptable costs on themselves, their people, or their nation. Opponents who do not really believe a retaliatory attack will occur are not deterred.Moreover,opponents must be rational -opponents must weigh the potential costs and benefits of their actions and choose a course of action that does not result in cots that exceed gains.Opponents who are irrational -who do not consider the costs of their actions to themselves,or their people, or their nation -are not deterred.