Since Hiroshima and Nagasaki - the world has been incredibly luck luck lucky
Is the world likely to go another 70 years without nuclear weapons being used? The short and troubling answer is no. Even worse, the potential for such use has increased in recent years and seems likely to rise further. The potential for use is least among those that maintain the largest inventories of nuclear weapons and have possessed them the longest. The chance of the five formal nuclear weapon states — the US, Russia, China, Britain and France — deliberately using such weapons is minuscule.And yet...
Though many states are downsizing their stockpiles, Asia is witnessing a buildup; Pakistan has the fastest-growing nuclear program in the world. By 2020, it could have a stockpile of fissile material that, if weaponized, could produce as many as two hundred nuclear devices. South Asia is the region most at risk of a breakdown in strategic stability due to an explosive mixture of unresolved territorial disputes, cross-border terrorism, and growing nuclear arsenals.
Emerging technologies such as missile defenses, cyber and antisatellite weapons, and conventional precision strike weapons pose additional risks, and could potentially spur arms races and trigger crises.