The deployment of nuclear weapons has been a critical problem for the NATO alliance. Opposition to nuclear tests within the Southern Hemisphere has developed with the creation of a South Pacific Free Zone and the decision by the New Zealand Government to ban port visits by vessels believed to be carrying nuclear weapons. This attempt to disengage from nuclear deterrence provoked a crisis in the ANZUS alliance with Australia and the United States that has been closely followed by political parties and pressure groups in the Northern Hemisphere. This first major study of nuclear visiting examines the questions of principle at issue, the evolution of the ANZUS crisis and its implications for the Western alliance structure as a whole. The author assesses the degree to which the ''nuclear free virus'' in the South Pacific might be catching and relates this work to some of the most pressing international issues of our time.