Preventing Coups and Seeking Allies: The Demand and Supply of Alliances for Coup-Proofing Regimes

Prevailing accounts of alliance formation emphasize either external threats or domestic politics, without an explicit consideration of how the two factors might interact. Instead, this paper theorizes about a specific type of interaction: coup-prevention strategies in nondemocratic regimes and external threats. Through quantitative analyses using the Alliance Treaty Obligations and Provisions (ATOP) and the State Security Forces (SSF) data, we find that “coup-proofing” reduces the probability of alliance formation when potential allies are under high external threat and that this effect is driven by the coup-proofing regime’s reduced capability to defend their allies, rather than the regime’s increased vulnerability to aggression. Furthermore, we find evidence for the interactive relationship at the negotiation stage of alliance formation. Upon entering an alliance, a coup-proofing regime facing a higher level of external threat offers more policy concessions to the ally, whereas an ally under higher threat could make fewer concessions to the coup-proofing regime. Our study highlights the way nondemocratic domestic political institutions can interact with external threat to shape states’ alliance behavior.