It may sound strange to say it, but nuclear weapons are perhaps the only weapons ever developed that have actually SAVED lives. Ignore the Japan thing, because thats a big quagmire of political incorrectness I dont want to get into. Look at the 60 years since then - without the threat of atomic attack, would there really have been 60 years pf peace among the developed western nations? In 1945 you had the two biggest military forces in history parked about a mile from each other in Germany, each spoiling for a fight with the other. That war never came, because within just a couple of years both sides had begun a nuclear arms race that made any open conflict a risk too far. Yes, conflict was shifted into supporting other minor wars in other nations - but those conflicts already existed. I believe the simple fact is that without nuclear weapons World War Three would have followed very rapidly on from World War Two, probably in the early 50's. It wouldn't have been an atomic war, but it would have finally and completely devastated Europe and cost many more millions of lives. Without nuclear weapons would the Cuba crisis have been so important that it led to the installation of the USA/USSR presidential hotline, and the first real communication between the two regimes. Would 'the Cuban Tank Crisis' have been quite so much of a threat? The first steps towards defusing the conflict between the two ideologies came because of fear of atomic weapons. Without the threat of nuclear weapons, India and Pakistan would already been knee deep in dead bodies from a real shooting war. AND Without the fear of atomic devastation and the massive loss of civilian life it would inevitable entail - would there really have been such a massive popular support for anti-war organisations and causes. Nuclear weapons made certain that the fear of war was relevant to every single person, and surely did a great deal to change public opinion. If you look back at the impact of nuclear weapons, the deterrence theory has proven successful in preventing wars between states by raising the stakes to unacceptable levels. Their legacy is positive HOWEVER While nuclear weapons have in the past prevented states from going to war, I think in future the threat will be from non-state actors and in those cases deterrence simply doesnt work. They have prevented major wars between industrialised nations, and continue to prevent open conflict in cases of India/Pakistan (and probably the US would be in North Korea by now if they didnt have the threat of atomic weapons), but if they come into the hands of non-state actors, groups who do not have to a civilian population or national infrastructure that atomic weapons can be used to attack, then the threat of them actually being used becomes significantly greater.