Natural disasters and their impact on cooperation against a common enemy


Economics, Finance and Quantitative Analysis

Document Type


Publication Date



We develop a simple game theoretic model to study the impact of a natural disaster on the coordination of defensive efforts by a target state (G) and an ally (A) in relation to the choice to stage an attack by a terrorist (T), to examine how the realization of a natural disaster can impact strategic choices in such a setting. We focus on “long term impacts” in which a natural disaster increases costs of defensive efforts for G. When costs for G are higher in this way, the optimal choice by A to provide assistance or not and the ultimate optimal choice by T to attack or not could be altered. For all possible parameter values, a unique Subgame Perfect Nash Equilibrium for the specified sequential move game is identified. A comparative statics analysis is conducted to determine how the natural disaster could alter the equilibrium outcome with respect to: (i) whether A chooses to provide assistance or not and (ii) whether T chooses to stage an attack or not. We show that for a natural disaster of sufficiently small magnitude, we could possibly realize one of two distinct counter-intuitive outcomes in which a natural disaster leads to: (i) A not providing assistance which otherwise would have been provided or (ii) T not staging an attack which otherwise would have been staged. That is, after a natural disaster occurs, it could be that (i) the ally of the target of a potential terrorist attack is less likely to provide defensive support or (ii) a terrorist attack is less likely to be launched.

Journal Title

European Journal of Operational Research

Journal ISSN






First Page


Last Page


Digital Object Identifier (DOI)