Summary

The steps-to-war theory maintains that war results from the issues under dispute and how states handle these issues. Its foundation rests on the territorial explanation of war, which argues that territorial issues are more conflict-prone than non-territorial ones because these issues constitute a salient security threat that realism recommends be addressed via power politics (i.e., the use of force, including alliance- and armament-building). When states employ power politics, however, the dispute festers, thereby causing recurring militarized conflict; creating feelings of threat, enmity, and competition (i.e., rivalry); producing counter-alliances and arms races; and generally building the more hostile, war-prone world that states originally sought to avoid. Each step taken—from a territorial dispute to rivalry (i.e., recurring militarized disputes) to alliance-building to armament building—therefore increases the probability that war will occur.

Existing empirical evidence supports the steps-to-war theory’s predictions in numerous ways. Tests of the entire theory, for example, demonstrate the dangerousness of territorial disputes, the tendency to manage territorial disputes via power politics, and that individual steps reinforce one another. Other bodies of research connect the individual steps directly to the likelihood that war will occur or highlight the connections between these individual steps—much as the theory predicts. Despite strong empirical support, however, much work remains to be done. Future research should consider the sequencing of the steps to war, investigate why the effects of certain steps vary across different epochs (e.g., alliances differ in their effects on war during the 18th and 19th centuries), identify the alternative paths to war, and study the paths to peace more explicitly—as obtaining peace may not be as simple as removing the known causes of war.