Previous studies of political decision making have used only static choice sets, where alternatives are fixed and are
a prioriknown to the decision maker. We assess the effect of a dynamicchoice set (new alternatives appear during the decision process) on strategy selection and choice in international politics. We suggest that decision makers use a mixture of decision strategies when making decisions in a two-stage process consisting of an initial screening of available alternatives, and a selection of the best one from the subset of remaining alternatives. To test the effects of dynamic and static choice sets on the decision process we introduce a computer-based process tracer in a study of top-ranking officers in the U.S. Air Force. The results show that (1) national security decision makers use a mixture of strategies in arriving at a decision, and (2) strategy selection and choice are significantly influenced by the structure of the choice set (static versus dynamic).