Except for common sense, which discredits the whole damn thing. No one has still explained how the PRC could keep a protracted invasion going, even if they committed a majority of their forces....it just doesn't make sense, and though the Fallout World has some strange facets, even it is somewhat grounded in reality.
China is one of the few countries on the face of the earth that could actually match America's military.
They have nearly 3 times as many troops as America does, and were fairly good at jurry rigging vehicles like tanks out of mining equipment. Its not unreasonable to assume that the faltering America would be hard pressed to force back an army 3 times larger then it when they were in the resource wars.
Keep in mind that our American armed forces are an entirely dedicated, very well trained volunteer force...China's army men, however, are mostly forced into it and aren't too well trained. Yes, they have more men, but ours are better.
We were even superior to the Chinese in nuclear weapons. Remember, Stalin and the Soviets refused to give Mao the blueprints for building an atomic bomb. He, of course, threw a hissy fit and forced his scientists to build their own models...which were inferior to Soviet and American designs. Of course, that's in the past now that we have ICBMs, but who's to say that the same type of thing didn't happen for other new weapons such as space weapons like B.O.M.B. 001?
I'd guess, once again, things were totally flipped. The USSR got some free market reforms in the 1970s, then started developing warm relationships with us once they realized how crazy the Chinese were. In the real world, the Chinese declared that the Soviets were essentially 'posers' and were their greatest enemy. The Soviets and Chinese are under different flavors of communism, so I doubt the two would continue to be allies.
Once the United Nations dissipated, the European Commonwealth and the Middle East fell apart and a bunch of countries started to go bankrupt, that likely gave China the freedom to invade anything they wanted, therefore marking the beginning their frightening plan of world domination. Then, of course, that backfired when their supply lines broke down, the United States developed power armor and the countries they annexed started fighting back with the help of Warsaw Pact/U.S. forces.
I'm definitely not a fan of the Soviet Union, but it's not like we hadn't banded together in the past to fight a bigger threat. Remember World War II, anyone?