A nuclear war is devastating, but it does not mean the end of worlds. The biggest blast from a modern nuclear warhead would probably not carry past a radius of 10 miles since most of the force would be dissipated upwards. But that is still enough to cause immense geographical, economical and human tragedy, but nuclear weapons cannot win you wars. Suffice to say if an all out war is fought between the USA and China, it will go full scale nuclear, China will first bear the brunt of the damage from the USA forward deployed forces, they will then retaliate on all regional USA bases, and use ICBMs on the USA mainland, but the main battle will be the control of the pacific. USA without any forward deployed forces cannot win the war, so like i said Western Europe is not at your doorstep, the thread is entirely pointless.