Preventive wars are commonly defined as wars initiated by a major power to preempt an anticipated disadvantageous position in terms of resources or military capabilities owing to the differential growth rates of countries. This essay extends a game-theoretic model of the balance of power to admit differential growth rates and also to permit countries to adjust their investments for the future. After establishing the conditions for equilibrium investment strategies, we then examine the properties of the nation-system that this equilibrium implies. Specifically, using a two-period model, we are interested in those first-period equilibria in which, because their sovereignty is subsequently threatened, countries will prefer to instigate a preventive war. We conclude by arguing that, although differential growth rates and the period 1 equilibria that initial resources imply can threaten the sovereignty of countries, there are a variety of coalitional strategies available to countries and that only some of them imply preventive war.
