Rethinking Reassurance: The Importance of Military Capabilities in Credibly Assuring Allies

41 Pages Posted:

See all articles by Brian Blankenship

Brian Blankenship

University of Miami

Erik Lin-Greenberg

Massachusetts Institute of Technology

Date Written: February 19, 2021


How can states most effectively reassure their allies? Despite massive investments to assure allies of Washington’s willingness and ability to defend them, the effectiveness of reassurance measures is uncertain. The limited existing research assessing reassurance effectiveness focuses on the role of resolve in making security assurances credible, sidelining important questions about the role of capability. We argue successful reassurance hinges not only on a patron’s willingness to defend an ally, but also its capability to do so. We introduce a new typology of reassurance measures based on variation in military capability and resolve, and analyze their effectiveness using an original survey fielded on European foreign policy elite and a case study of U.S. and NATO reassurance initiatives in the Baltics. We find that capabilities matter as much as resolve, with relatively limited deployments of offshore and high-tech capabilities reassuring allies just as much as tripwire forces.

Keywords: Reassurance, Alliances, Signaling, Capability

Suggested Citation

Blankenship, Brian and Lin-Greenberg, Erik, Rethinking Reassurance: The Importance of Military Capabilities in Credibly Assuring Allies (February 19, 2021). Available at SSRN: or

Brian Blankenship

University of Miami ( email )

Coral Gables, FL 33124
United States

Erik Lin-Greenberg (Contact Author)

Massachusetts Institute of Technology ( email )

77 Massachusetts Avenue
Building E40, 4th Floor
Cambridge, MA 02139
United States


Do you have a job opening that you would like to promote on SSRN?

Paper statistics

Abstract Views
PlumX Metrics