Dermot Boyle

"The size of a deterrent force must be related to the value to an enemy of the prize being protected. For example, suppose - I repeat, suppose - Russian leaders were prepared to sacrifice half their country in exchange for the removal of the USA from the competitive scene. Then, for the American deterrent to be usable, it would have to be demonstrably capable of destroying far more than half Russia in retaliation. But Russia would not be prepared to accept anything like the same damage in exchange for the removal of the United Kingdom. Therefore, a much smaller retaliatory force can give as much or greater security than the USA achieve with their vast nuclear capability."