The effects of uncertainty in strategic analysis are generally not well understood, but are increasingly important in relating the strategic calculations by means of which we evaluate the adequacy of our strategic forces to the deterrence of attack in the world of real political leaders, in real crises. Assumptions must be made about many unknowns and uncertainties—ranging from the behavior of national leaders to the technical characteristics of weapons systems—in order to make the problem calculable. The assumptions we make for purposes of analysis, however, are not necessarily the same as those that political leaders can make in considering the actual use of nuclear forces. This distinction is at the root of the relationship between strategic analysis and real-world deterrence. Systematic examination of the uncertainties in strategic analysis, therefore, can help us to better understand the difference between our analytical model and the real world, and hence to put our strategic problems in better perspective.