Modern warheads are smaller, not larger - everybody knows that. And what "sophisticated" means is better targeting, which is why smaller weapons can be used. Th

Modern warheads are smaller, not larger - everybody knows that. And what "sophisticated" means is better targeting, which is why smaller weapons can be used. Those things seem to point away from blowing up the entire world. I don't know if it's true, but there was a rumor that if one wanted to, it would be technically feasible to make a hydrogen bomb of unlimited size - e.g. crack the planet in half. However, that path was not taken.