While Just War Theory is the best account of the morality of war, along with many others, the author does not believe that actual decisions by states to go to war are often, or at all, informed by such ethical considerations. A much more plausible view is given by the doctrine of realism, familiar in international relations. This chapter discusses realism as a basis for evaluating weapons research in wartime, and here the author refers to Clausewitz views of war and politics. His conclusion, in a nutshell, is that since states on this account are only concerned with their own interests, there can be no assurance that the products of weapons design will not be used for aggression.