It all changed when: Albert Einstein decided that World War II (yep, that again) was something the world could have done without, and travelled back in time from 1946 to 1924 to kill Hitler. Unfortunately, in a rare instance of the Nazis actually being useful, it turned out that their now-deleted existence held back aggressive Soviet expansion. Without Germany to get in the way, Russia made a bid for world domination, bringing out WWII anyway, just in a different flavour.
And then in Red Alert 3, the losing Russian side kickstarted another new timeline by going back and killing Einstein before he could develop the Allies' war-winning tech. Not being privy to Eistein's own time-travel mishap, they had no idea how badly wrong that sort of thing can go, and ended up rebooting a buggy future, namely one suffering from an unwanted case of eastern aggression. Cue WWII v3.0.