The U.S. Department of Energy's National Nuclear Security Administration (NNSA) has just made a big announcement: they've finished building a key part of the W87-1 nuclear warhead, something called a "plutonium pit." This pit is a radioactive core that acts as the first-stage trigger to start the explosion in a thermonuclear bomb, a devastatingly powerful type of nuclear weapon. While this may sound like a technical achievement, it’s only the first step in a much larger and more complicated pro...