It has been generally accepted in recent years by strategists that the possession by each of the two Great Powers of nuclear weapons, of sufficient destructive power to cause unacceptable destruction to the opposing side, has constituted a deterrent to either side against the use of these weapons – and a deterrent also against aggression generally, whenever there was a fear that this might lead to the use of nuclear weapons. As long as the cold war seemed to be forming the world into two blocs of opposing nations grouped round the major nuclear powers, some calculation of the risk of nuclear war entered into the strategic calculations in most areas of conflict, thus restraining the use of violence and the spread of war.

For a time, there seemed to be some hope of stability in this situation. Of course there was always the risk of war by accident, and the danger of a technical breakthrough in the arms race which would destroy the symmetry of the balance; but if only these dangers could be overcome, there seemed to be some prospect of a stable bi-polar world. Consequently, all the attention of the politically involved peacemakers focussed on means of slowing down or stabilising the arms race between the major powers, and of improving safeguards against the risk of war by accident.