Ronald Mason was the Chief Scientific Adviser at the British Ministry of Defence from 1977-1983. In the interview he discusses the modernization of British nuclear forces. He describes the process of deciding the best way to replace the Polaris missile through cooperation with either the United States or France in order to achieve a British independent deterrent. Among the varied challenges are: assessing new technologies, convincing the Americans to cooperate, and defining the nature and requirements of an independent deterrent. He discusses questions of nuclear strategy in light of the forthcoming Intermediate Nuclear Forces (INF) Treaty.