Nazism has always been an Anglo-American creation both as an ideology (eugenics and social Darwinism) and politically in an anti-communist function.
When they realized that their pawn would fail to conquer Russia they decided to intervene to prevent the whole of Europe from going communist.
They disavowed Nazism and indeed for decades they have been constructing the narrative through Hollywood that the Anglo-Americans were the archenemies of Nazism and that they defeated it with the help of the USSR.