China and the USSR were at war due to being invaded.

the chinese leg of the conflict is particularly goofy.

China had two, or three parties at one point, all fighting for control over the country. There was the communist party (backed by the soviets) There was the democratic party (backed by the US) and then there was also japan doing it’s thing trying to take over china as well.

Prior to this there was the russo japanese war, which was an equally big shitpost, the russians having been fucking broiled by the japanese over it, though a different story.