China cannot militarily involved itself in any conflict around the world. It doesn't have the capacity yet. China can only provide defense weapon and raw missile materials. By 2035, China will have 6 aircraft carrier then they can start talking.
Right now, China can put up a great fight against US if they dare attack them in their soil. U.S will not win in that scenario.
What China is doing is basically amassing or absorbing as much Chi as possible like Goku, then release it all at once. It will take awhile.