Britain's small Polaris force had to remain credible as Soviet anti-ballistic missile defences improved. The reading traces concern about Moscow's defences from the 1960s into later radar and interception developments. Simply choosing an undefended city would not answer the same strategic requirement as retaining the ability to threaten Moscow. Chevaline sought to preserve that capability by improving penetration of the defensive system. The problem involved the number of available missiles, the protection of their warheads, and the target against which deterrence was judged. An estimate quoted in the reading assumes 70 percent missile reliability and requires four Polaris missiles to inflict sufficient damage on Moscow without missile defences. Soviet interception raised the force requirement further.
Notable Point · 3:41:16-3:43:43
Chevaline and the Resolution-class deterrent
Soviet missile defences around Moscow created a penetration problem for Britain's limited Polaris force and drove the case for Chevaline.