ABSTRACT
Defence against ballistic missiles has always been closely associated with the credibility of a nuclear retaliatory capability. This is especially so for a modest nuclear power like Britain, whose ‘minimum’ deterrent has at the same time been both relatively small and reliant upon a single means of delivery. Any such system is potentially vulnerable in two ways. It may be susceptible to pre-emption before it can be launched, and it can be countered in the air before it reaches its target.
