They've saved millions of civilian lives as well. A fully conventional war in Europe would kill millions of civilians. Had we never invented nuclear weapons, we would have had a third major land war in Europe in the 20th century. If you think World War 2 was horrible, imagine the full conventional military might of the Warsaw Pact and NATO going head to head in the 60s or 70s. The German Army was largely horse drawn during WW2. The last time the major powers went at it, our technology allowed us to kill each other in such great numbers that we lost track to the nearest 10 million. That alone is why need nuclear weapons. Imagine fighting a war and in the aftermath not nowing if the entire population of Greece still exists.