Replication Data for: Do Alliances Deter War?

This research note reexamines the ongoing debate about whether security alliances help prevent conflicts. It specifically reevaluates recent scholarly exchanges between deterrence and Steps-to-War studies. Deterrence scholars argue that alliances reduce the likelihood of conflict initiation, while Steps-to-War scholars contend that forming an alliance can actually incite conflict. Both sides provide evidence to support their theories by analyzing the effectiveness of defensive pacts in deterring or failing to deter militarized interstate disputes. However, recent studies have overlooked testing and reporting whether alliances prevent the most destructive form of conflict: war. This omission is surprising, given that the primary goal of alliances is to prevent war. This research note conducts a canonical directed dyad-year analysis of 1,077,992 observations from 1816 to 2000 and finds compelling evidence in support of deterrence theory, but not for the Steps-to-War theory. As a result, this empirical research clarifies the debate between these two leading theories in international relations.