Trivial Tripwires?: Military Capabilities and Alliance Reassurance

How can states most effectively reassure their allies? Existing studies assessing signals of commitment focus on the role of resolve in making assurances credible. This sidelines important questions about the role of capability. We argue that reassurance effectiveness is the product of both capability and resolve, and suggest that high resolve cannot offset low capability. We introduce a new typology of reassurance measures based on the interaction of military capability and resolve, and test which types of measures are most reassuring using an original survey fielded on European foreign policy experts and a case study of US and North Atlantic Treaty Organization reassurance initiatives in the Baltics. We find that high-resolve, low-capability signals such as tripwire forces in allied territory are not viewed as any more reassuring than high-capability, low-resolve signals such as forces stationed offshore. Our study casts doubt on the reassurance value of tripwires and contributes to scholarship on interstate signaling.