China isn't militarily supporting Russia or Ukraine. Ukraine's drone army is built from cheap Chinese drones. China is neutral. The argument that it hasn't sanctioned Russia means it is a party to the war on Russia's side is an argument of the form "if you aren't with us, you are against us." But then, you'd think the US would levy the same kind of vitriol at e.g. India.
China is led by a General Secretary of the Communist Party's central committee. Taiwan and China are recognized by the United States by international treaty as one country.
China is "attacking" the US? The US and China are in economic warfare (an economic war started by the United States under the Trump Administration). The reason for this is the US sees China's economic rise as a threat to its global position.