Audience costs and the risk of war under effective brinkmanship deterrence

This study, using a game-theoretic model between two nations (a challenger and a defender) presented by Yamamoto (2024), clarifies how the creation of audience costs affects the escalation of brinkmanship and the probability of war under incomplete information regarding the challenger’s resolve (weak or strong). Numerical simulations suggest that, when audience costs are high enough, the defender may stochastically combine insufficient coercion with appeasement in response to the challenger’s escalating military provocations. This randomization is adopted to prevent the weak challenger from completely deviating to escalating provocations by pretending to be strong in his resolve. However, in addition to accidental war resulting from the failure of appeasement, it could cause deliberate war as a result of the failure of coercion. While the expected level of military provocations by the weak challenger has an inverted V-shaped relationship with audience costs, the probability of war is positively correlated with these costs.