This article explores Welsh protests against chief policies of the British nuclear state, especially nuclear deterrence, civil defence and its close relationship with the United States. It contributes to the social, cultural and political histories of the postwar British nuclear state by further demonstrating the plural character of protests across and within the British nations. It shows that, while local authorities, individuals and extraparliamentary groups certainly dreaded the prospect of nuclear war, the nuclear weapons issue often presented them with a vehicle to protest against British government policy more broadly.