Our thousands of nuclear weapons were designed, tested and built in the 1960s, ’70s and ’80s to win the Cold War. None of these weapons has been tested since 1992, over a quarter century ago. Nor has a single new weapon been designed, tested or built during this same period. The tens of thousands of active nuclear weapons scientists in our three nuclear weapons labs have never designed, tested and built a nuclear weapon. Nuclear weapons are the most complex systems ever created by man. The detonation of a nuclear weapon is so complex that there are many activities and...