When the capabilities available to nuclear aspirants are carefully scrutinized, the dimensions of the proliferation threat may not warrant the note of desperation often heard. U.S. scientists and politicians have seriously understated the staggeringly high costs for a country to achieve a serious military nuclear capability, and the limits of resources, engineering skills, and production facilities. Nations such as India might be lured into military nuclear efforts by such drastic underestimation of the true cost. Possession of fissionable material is only a short step on a long road. Moreover, nuclear capability has not been associated with political success during the 1960s. Advanced industrial countries cannot be denied peaceful nuclear energy, and U.S. refusal to help would only inspire resentment. The real threat is to the small and less-developed countries of the third world: some might seek a primitive nuclear force for purely local use. Less-developed countries could be prevented from having even simple nuclear facilities, but only if all the nuclear powers and advanced nations cooperated in withholding the components and technology. (Prepared as an address to the regional American Assembly, meeting at the University of Notre Dame, March 1967.) 22 pp.