ABSTRACT
This chapter considers the nuclear threshold as an especially stark and simple example of the role of constraints, restraints, and thresholds generally. Of course, some differences arise just because of the special saliency of the nuclear threshold. The chapter argues that the US, the European nations, and the USSR should prefer that the nuclear consensus hold that nuclear weapons are, by and large, not useful except as a deterrent or response to other nuclear weapons. The Korean War is often taken as a prototype of a situation in which the US revised a declaratory policy which, if literally followed, would have made the North Korean invasion perfectly safe. At least in peripheral and small conflicts, a practical general availability of nuclear weapons and few inhibitions against their use would seem to put a premium on good capabilities for: using blackmail and threats; surprise attacks "out of the blue"; anonymous attacks; other concealment of forces and intentions.
