The Department of Homeland Security (DHS) has adopted a focused approach to risk reduction. DHS is moving increasingly to risk analysis and risk-based resource allocation, a process that is designed to manage the greatest risks instead of attempting to protect everything. This report applies a probabilistic terrorism model that is broadly applied in the insurance industry to assess risk across cities, to assess risks within specific cities, and to assist intelligence analysis. Among the authors’ conclusions: Terrorism risk is concentrated in a small number of cities, with most cities having negligible relative risk, so terrorism estimates such as those described in the report should be incorporated into the grant allocation assessment process. DHS should consider funding the development of city profiles of major metropolitan areas receiving DHS preparedness grants. It should also develop descriptions of terrorist attack planning and operations that can be used to translate estimates from risk models of likely attack scenarios into detailed recommendations. Finally, DHS should develop tabletop exercises to test the scenarios and provide feedback.
