Your challenge should you choose to accept it is to create a war where the Union of Soviet Socialist Republics(communist) and the United States of America(democratic, non-communist) are allied together against the People's Republic of China(communist) with a POD after 1900. The PRC must be a credible threat to both nations, and even with its defeat, some sort of Chinese nation must still exist. Bonus points if the POD is after WWII and/or the Cold War ends because of this