In 19 39, the chinese win a couple of battles against japanese. They weren't ready for that yet but had a huge contingent of officers who really wanted to attack soviet union. The war in china as a proxy war not just for the united states, but for great britain, and the sovietunion,. All of whom have an interest in keeping japan bog down. Got their wish unfortunately - there were incidents or clashes between the red army and the japanese army up there which turned out to be very bad.