former Trade consultant at International Relations
In the exceedingly unlikely event of war between the US and China or Russia, the world would fall mostly into 4 camps.
Allied with the United States.
This group would represent the overwhelming majority of the world’s economic, military, political, social, and industrial power. It would include NATO, most or all of the EU, Japan, Australia, South Korea, as well as dozens of countries from Latin America, Africa, and Asia. These nations would contribute some significant degree of military, economic and diplomatic support.
Friendly to the United States
Most nations that don’t fall directly into the “allies” camp are still economically dependent on the US and/or the other nations in that camp. Therefore they would back up embargoes, provide some degree of material support in order to stay on the good side of the allied nations, and likely move closer to the Allied camp as the conflict continued.
We’ll mostly not take sides, even if we sort of do
There are a few nations like India, Pakistan, Kazakhstan, or Myanmar that could find themselves in a difficult spot. Due to popular internal sentiment or proximity to China/Russia they might not find it wise to take sides. That doesn’t mean they won’t help the allies at all, it will just be done covertly. Jordan in the first Gulf War is a perfect example of this sort of country. They smiled at Iraq and pledged friendship to pacify their population, while backroom dealing with the US.
We’ve got your back!
China and Russia really have almost no allies in this category. What they do have are broken and ineffectual (Syria, Belarus.) Basically, no nation of significant consequence could be expected to aid either nation if they inexplicably went to war with the United States.
works at Fanfiction.net
In the insanely improbable event of any such war (and neither Russia, nor China, nor the United States are crazy), China’s allies are pretty small and limited, namely North Korea. Who, aside from the mass of bodies they can provide in uniform, bring very little of any real value to the table. (As compared to America, who has a considerable number of regional and international allies, all of whom bring plenty to the table)
As for Russia, again I don’t think they actually have any real allies that I am aware of.