Your post is very misleading on a number of points..
The CPA has an anti-fascist position.
The Soviets (communists) and the Nazi’s (called nation socialists but really fascists) were always diametrically opposed - mortal enemies - this is the left vs right. Their non-aggression pact and subsequent carving up of Poland merely satisfied their mutual greed. They weren’t ‘aligned’ in any other way except possibly to establish a truce while the West bore the brunt of Nazi aggression.
Russia didn’t ’join the war on Germany’ - the USSR was invaded by Nazi Germany - and this was always going to happen, it was only a matter of timing…
