Good point. If Stalin had made peace with Hitler, it would have been very difficult for us to defeat the Third Reich. I think the Russians lost @20M fighting the Germans.
It was toward the end of the War that FRD irked me, when it was already apparent that Hitler would lose the war. That was when FDR got closer with Stalin and both of them shunned Churchill. FRD either was a closet commie or he was totally blind. Churchill could see that Eastern Europe was trading one tyrant for another and FDR would not listen.
Roosevelt was a product of the First World War, as President Wilson's Under Secretary of the Navy.
His responsibilities included naval intelligence, counter-espionage and counter-sabatogue.
Literally, Roosevelt hated Nazi Germans -- in the same sense that others were anti-Semitic or racist, FDR was anti-German.
During the war he believed they needed to be bombed back into the stone-age -- with the A-bomb if necessary, remember that was its original purpose.
Domestically, FDR kept a very close watch on Nazi related groups, their activities and spies.
By stark contrast, FDR had no fear of the Russians, Soviets or International Communists.
He considered them our friends, and did little or nothing to protect us against them.
This turned out to be the right strategy for defeating Hitler at minimum cost to the US, but with tragic, tragic postwar results especially in Eastern Europe.