In 1945, the US War Department realized that its soldiers stationed in Europe fighting the Nazis probably needed a good pamphlet explaining what fascism was, and how it occurs ...

... so they wrote one

and in it, they noted that America was not at all immune to this

So they explained how fascism would come to the US

Heather Cox Richardson writes about it in the latest edition of her newsletter: https://heathercoxrichardson.substack.com/p/october-26-2024