The danger of accidental war was demonstrated in World War I and was recognized in its aftermath. The experience of World War II, however, obscured the lesson and powerfully reinforced the traditional concern of intentional aggression. Over the ensuing decades, as the instruments of warfare acquired capacities for rapid and massive destruction, the military forces that wielded them were configured to deter or to defeat deliberate attack. Precautions were taken to assure that their enormously destructive power would not be employed without legitimate authorization, but those precautions were clearly subordinated to the purpose of deterrence. That effect was achieved and is plausibly credited with preventing at least the largest forms of deliberate aggression, but the accomplishment has enabled a massive accident to occur.
Overwhelming deterrence entails some inherent risk of inadvertent catastrophe.