Alliance Formation and Conflict Initiation: The Missing Link

Existing research on the connection between alliance formation and conflict initiation has explicitly focused on the direct effect of alliances on conflict by including some measure of alliance behavior as an independent variable in models of conflict behavior. Existing research misspecifies the relationship between alliances and conflict, because alliance formation and conflict initiation are shaped by many of the same factors (in particular, regime type and capabilities), and alliance formation decisions are endogenous to conflict initiation decisions. Thus, alliance formation and conflict initiation should be modeled in a system of equations where a set of variables shapes alliance formation and conflict directly, and indirectly affects conflict through the decision to ally. The author estimates a two-equation probit model that accounts for the endogenous nature of alliance formation decisions and, thus, for the indirect effects of variables like regime and power on conflict. Results suggest that the effect of regime on alliance behavior differs across time periods. Finally, the model provides evidence that the total effects of variables like power and regime on conflict are, in fact, mediated by how those variables influence the decision to ally.