Both the Russians and the US know that when it is over, there won't be anything left worth having. The problem children are Iran, China and North Korea.....
China does not worry me at all. If nothing else, they think before doing anything, and are expert at setting up alternatives. Iran and NK are complete reactives, no thinking at all, simple pull the trigger and never mind the consequences. The beauty of those two is that they will do their worst right out of the box. They will be promptly squashed. Flat. And thin.
It's about the money for most, the power for Iran and NK. As you said Ghrit, some nut job may pull the trigger but none of the superpowers will. Just no monetary gain in it.
I am with @ghrit on this. And, I would include Russia with China because if anyone knows the punch the USA packs - well - it is them. Iran and NK would/could do some damn 'knee-jerk' thing that will be their first and last launch but once those rockets start flying who is to say that some of the major players aren't drawn into the exchange. War is confusion even at the best of times. The Anonymous video is a nice chronological walk through history and I would bet it is very close to the truth as makes perfect sense why we got off the gold standard...no limit on how much paper they can print.
China plays the long game will prevail someday without having to fire a shot...or at least not the first shot...if our government continues operating thinking no farther ahead than the next news cycle.