§ The Prime MinisterThe 1958 United Kingdom-United States agreement for co-operation in the uses of atomic energy for mutual defence purposes, as contained in Cmnd. 537, and amended by Cmnds. 859, 4119, 4383, 6017, 7976 and 9336, remains extant. The 1963 Polaris sales agreement was adapted in October 1982 to cover the purchase of the Trident-II weapon system, and remains extant.