How can we know how badly the Russians would dislike an all-out war in which both sides were annihilated? We cannot; and the reason we cannot is not solely that the Russians are necessarily unwilling that we should know. On the contrary, circumstances may arise in which they are desperate that we should know the truth. But how can they make us know it? How can they make us believe that what they tell us is true? How can the prisoner being tortured for secrets that he really does not know persuade his captors that he does not know them?

Thomas C. Schelling, The Strategy of Conflict, loc. 278