TRIGGER WARNING: Wherein we talk about nuclear weapons.
For John, BLUF: Modern nuclear weapons are not that big—smaller than an SUV—but very powerful. Nothing to see here; just move along.
Here is the Wikipedia article on Trinity. At 5:29:45 on 16 July 1945 the United States tested its first nuclear device, the "gadget". It worked.
It also worked twice more, in different designs, over Hiroshima and Nagasaki. While it was touch and go for a while, those two weapons pushed the Japanese Emperor into agreeing to surrender, as long as the Chrysanthemum Throne was preserved. It was, but with General Douglas MacArthur as the "Shogun".
After the successful test Dr J Robert Oppenheimer recalled the words of the Hindu scripture, the Bhagavad Gita; where Vishnu says, 'Now I am become Death, the destroyer of worlds.' Dr Oppenheimer later said "I suppose we all thought that, one way or another."
Nuclear weapons are now part of the knowledge of man. They must be retained, for the purpose of deterrence, since trust is not yet a part of human nature. However, they must be dealt with carefully. Not setting off a nuclear war is an important goal. Conversely, being ready to respond in kind is a good deterrent.
Regards — Cliff