Entente versus Alliance: When Should States Be Friends but Not Allies?

Abstract

When faced with a common threat, states have various alignment choices. Formal alliances offer explicit military obligations of support. Others, such as the Triple Entente that preceded World War I, are more ambiguous understandings. These entente-like alignments make no formal pledges of armed support in the event of hostilities. However, they do not entirely rule out military support either. Why might states embrace this form of strategic ambiguity over firm alliance commitments? Our formal explication addresses this question via the prism of collective action. Our modeling efforts, combined with historical precedents, suggest that an entente might be a more effective alignment choice than a formal alliance for states to balance against powerful threats. An entente permits states to strike the middle ground between entrapment and deterrence. The strategic ambiguity inherent in these two seemingly self-contradictory goals of an entente is a key component of its success as an alignment strategy, especially when external threats are large. However, asymmetry in strength between two states can result in divergent preferences between alliance and entente.