The “estimated weight of attack [from the Soviet Union] is from some 330 weapons in the megaton range…The weight of [a Soviet attack] would clearly be smaller should the West strike first, in which case the Soviets would be reduced to a retaliatory strike from their remaining forces”. A previous attempt was made by the Joint Intelligence Committee to assess the size of this “which indicated a minimum figure in the region of 40 weapons against the UK in 1964”. The attached annex now states that ”the minimum attack force against the UK may rise to 100 missiles and 50 medium bombers by 1968”.
Annex to the above: ‘Soviet retaliatory strike capability against the United Kingdom’, 9 July 1964: “Even after receiving a full scale surprise attack by the West, sufficient Soviet strategic nuclear strike forces would survive to inflict extremely grave damage on the United States and to devastate large parts of Europe… In mounting a retaliatory strike… we would expect the medium bombers to be directed against centres of population rather than counter-force targets”.
National Archives: DEFE31/54
Defence Intelligence memorandum, “Soviet strategic nuclear delivery capability”, JIC (66) 65 draft, 5 October 1966
“The change that is likely to create most discussion is that by end 1970 the Russians will probably have exceeded the West in total numbers of strategic nuclear delivery vehicles. There would appear to be little cause for excitement or indeed for ‘appreciations of the implications’, both sides have been in the position of having more than enough for some time [sic]. More important is that the West will still have a superior strategic retaliatory capability”.
National Archives: DEFE 31/56