Cooperation under the Security Dilemma

International anarchy and the resulting security dilemma (i.e., policies which increase one state's security tend to decrease that of others) make it difficult for states to realize their common interests. Two approaches are used to show when and why this dilemma operates less strongly and cooperation is more likely. First, the model of the Prisoner's Dilemma is used to demonstrate that cooperation is more likely when the costs of being exploited and the gains of exploiting others are low, when the gains from mutual cooperation and the costs of mutual noncooperation are high, and when each side expects the other to cooperate. Second, the security dilemma is ameliorated when the defense has the advantage over the offense and when defensive postures differ from offensive ones. These two variables, which can generate four possible security worlds, are influenced by geography and technology.