An Analysis of Short-Term Responses to Threats of Terrorism

Two important defensive mechanisms available to governments combating terrorism are warnings and the deployment of physical resources. Warnings are relatively inexpensive to issue but their effectiveness suffers from false alarms. Physical deployments of trained security personnel can directly thwart attacks but are expensive and need to be targeted to specific locations. In this paper, we model the joint optimization of defenses against terrorist attacks based on warnings and physical deployments when there is uncertainty in the timing and location of attacks. We model both private warnings issued to security forces and public warnings broadcast to the general public. By structuring the trade-offs faced by decision makers in a formal way, we try to shed light on an important public policy problem. We show that the interaction between the use of warnings and physical defenses is complex and significant. For public warnings, we also model the possible response of terrorists and show how these responses influence the effectiveness of such warnings.