Do you believe there is a chance bigger than 0.0 for Russia to go to war against the US over Iran? Let's be serious.
If, by any chance, Israel were to attack Iran (and I don’t think that’s a realistic option at all), I’m sure Iran wouldn’t be left without the help of its allies, and I mean China and Russia in the first place. Although Iran is under sanctions, China and Russia have no reason to enforce those sanctions, when they themselves are victims of something similar.
Do you really think China has such goals?
China dreams of restoring / expanding its status, the status of a center of influence in Asia! China is now very important to the maximum weakening of Russia, the same Iran, India. The first one is a resource appendage of China, historical Chinese territories - to support patriotism (Siberia is ours!). Iran is the center of destabilization in the region. India is a real competitor in many areas. And it goes without saying that he is categorically not interested in resisting in a showdown with the United States, in spite of some ideological confrontation. China is the east, and the east has always been logical, smart and cunning!