Alliance Formation in Regional Space: Shifting the Battlefront Between Competing Hegemonial Powers

Motivated by the history of military alliances during and after the Cold War, we study the sequential expansion of the hegemonial alliances of two great powers. Geography matters for the allocation of the collateral damage of a future military conflict. Current frontline countries bear a major burden. They would prefer to pass this collateral damage on to new members. This motive can drive expansion, which comes to an end only when all remaining non-affiliated countries have been absorbed by one of the two alliances. Those countries are willing to make concessions as part of the accession negotiations, and the overall value of the concessions can reach multiples of the actual collateral damage of military conflict. As a result, alliance expansion may continue beyond what would be optimal from a security perspective.