Revolutions in Reassurance: The Effect of Military Tech on Alliance Assurances

• In Event: Determinants of National Defense

Abstract

How can states most effectively reassure their allies? The United States has invested billions in exercises and foreign military presence in Europe and Asia aimed at reassuring its partners of its willingness and ability to protect them from a rising China, a resurgent Russia, and an erratic North Korea. Yet the effectiveness of these reassurance signals is uncertain. Existing literature on security guarantees largely focuses on the effectiveness of deterring adversaries, but partners’ perceptions of signals of commitment remain under-explored. We introduce a typology of reassurance measures which disentangles the mechanisms by which foreign-deployed military forces increase allies’ confidence in U.S. protection by separating out signals that reassure allies of U.S. resolve and signals that reassure allies of U.S. capability. We classify reassurance measures as either tripwires, shields, offshore, or drive-bys and demonstrations. We test our propositions using a mixed method approach that combines rich qualitative case studies informed by interviews with government officials and analysis of government materials with a novel comparative survey experiment fielded in the Baltics and the United States. Our findings will contribute to the academic literature on the credibility of threats and promises by identifying which signals have the greatest reassurance effect. Further, the results can help inform policy decisions on alliances by exploring not only what reassures, but also whether lower-cost alternatives to large overseas presence can be equally effective at reassuring allies.

Authors

• Brian Blankenship, University of Miami

• Erik Lin-Greenberg, Columbia University