Maralinga was now redundant, as the Australian Government's restriction on testing thermonuclear weapons had led to the development of the Christmas Island test site, where there was no such restriction, and its favourable winds carried fallout away. With the 1958 US–UK Mutual Defence Agreement, Britain also gained access to the Nevada Test Site, where the first British major test took place underground on 1 March 1962, but there was no certainty that Nevada would be available in the future. The 1963 Partial Nuclear Test Ban Treaty banned atmospheric testing, and no site was located at the Maralinga Range for underground testing; the nearest suitable site was on Aboriginal land away.