Russia is also a failing state with a crumbling economy and a demographic disaster unfolding, that is having issues pushing further than 50kms from its borders in a land war with the poorest European nation. They would only be a liability in a conflict against China.
There won't be any other front. Just stop fantasizing. Russia has the same regime as China. China is sponsoring Russia's war with Ukraine by buying Russian oil, supplying dual-use products, and providing diplomatic assistance to Russia. Why would Russia confront with China?
