Probabilistic modeling of terrorist threats: A systems analysis approach to setting priorities among countermeasures

Setting priorities among homeland defense measures is a difficult task given the large number of possible scenarios and the uncertainties about the probabilities and impacts of the possible types of attacks. This paper presents a model for setting priorities among threats and among countermeasures, based on probabilistic risk analysis, decision analysis, and elements of game theory. This model accounts for the probabilities of different scenarios, the objectives of both the terrorists and the US, and the dynamic competition between them. The model presented is useful for ranking countermeasures at a number of levels in the US government.