It would certainly be unnerving, but I would expect their command and control procedures to account for some amount of context. In this case, the context would

It would certainly be unnerving, but I would expect their command and control procedures to account for some amount of context. In this case, the context would be: "Holy shit guys, NK just launched a rocket that looks like it's headed for LA!" [3 minutes later] "And now the US just launched 14 rockets, and they might be headed for us, but they're probably headed for NK." China's best option is to wait and see, because if they decide to fire, and were wrong about China being targeted, they'll see another round of launches three minutes after that one, and those will be headed for China. They've played this all out. MAD really does work.