This paper considers the advisability of governments including in a national counterterrorism strategy efforts to deter chemical, biological, radiological, and nuclear (CBRN) terrorists. It assesses the deterrent value of several counterterrorism instruments by explaining the interaction between the elements of deterrence, the CBRN terrorism process, and available instruments of deterrence. The paper concludes that, while many counterterrorism strategies have potential deterrent value, what is lacking is a coherent, cohesive policy framework with which a "web of deterrence" can be cast. It attempts to provide the first step towards such a framework. To assist in identifying a set of decision points against which a strategy of deterrence can be applied, the basic model for CBRN terrorism includes: Ideology and Value Formation, Motivation, Planning and Information Gathering, Acquisition, Production, Deployment, Use, and Exploitation. Finally, the challenge facing policymakers is to use available instruments to support deterrence in an integrated and synergistic way. Figures, notes