There is also the famous question by HUAC congressman "Does mr. Euripides preach class warfare?". FDR was not a fellow traveler (what is this? McCarthy's argument?). FDR was a left-leaning US President, with a Cabinet probably full of "fellow travelers" (although I doubt a McCarthyst fellow traveler was something more than a not blatanty-racist alt-rightist). But Stalin was the Paramunt Leader of the Workers of the Wolrd and still he allied with Hitler. Why? Geopolitics. IMHO USA and USSR were natural allies in Interbellum World: two young countries, full of idealism, rapidly growing and natural enemy of the Old Colonial Europe. Both had lots of advantages in the end of colonialism: this made them allies against Churchill at Yalta IOTL. Both had lots of advantages in reduce european influence in the world: this made them allies against Churchill at Yalta IOTL. Both had lots of advantages in divide the world between themseves: this made them allies against Churchill at Yalta IOTL. If Japan was involved, both had lots of advantages in crush it to pieces: this made them allies in the Pacific. On the contrary, FDR had no advantage in an alliance with Hitler or with UK and France against Stalin: quod prodest? Of course, a military alliance was a no-starter, but a lend-lease or the like would be possible (and a good excuse for a Third New Deal). Even a simple embargo would do wonders. Aaaaaaaaaaaaaand, if Japan was involved, an embargo would easily provoke a PH. Almost everybody but Hitler: in Mein Kampf he said the worst tort of Versailles was Alto Adige (vol. II ch. 13 and the Zwei Buck), while Danzig corridor was a correct choice since it was inhabited by Polish (Santi Corvaja 1982) - I'll provide the quote in a second EDIT: done. I want to highlight that Hitler said so to silence a faction in German alt-right that pushed for Alto Adige even if it would cost Italian alliance. If a catholic austrian leaved South Tyrol for Itlay, he could leave Danzig corridor for Poland.