The Tripwire Effect: Experimental Evidence Regarding U.S. Public Opinion

Abstract

Claims about the deterrent role of forward military deployments often depend on the argument that attacks on troops stationed abroad will activate a “tripwire effect.” It is assumed that this effect would generate strong domestic pressure for further military intervention by the country whose troops have come under attack. In theory, the anticipation of a strong tripwire effect prospectively ties the hands of leaders, thereby bolstering the reliability of extended deterrent threats and promises. In this paper, we define the tripwire effect and use both conjoint and vignette survey experiments to evaluate its operation and magnitude among Americans. Results suggest that the tripwire effect is, at best, far weaker than many analysts and policymakers commonly assume. This finding raises serious questions about a core logic underpinning the United States’ forward military posture and highlights the need for more research on the deterrent functions of forward deployment.