What if in 1938, while the Hitler problem was just starting, Stalin invaded Eastern Europe while the other powers were distracted. Stalin suddenly annexes Finland, the Baltic States, Poland, Hungary, Slovakia, Czechoslovakia, and Austria. The latter two shatter Hitler's Anschluß and he declares war. The other powers get involved and declare war on Russia. This could have other RL-ly neutral nations become involved. For example, Turkey and Iran liberating Azerbaijan, Sweden having to retake Finland, etc.