It was pretty clear at that point that if the US didn't enter, the USSR would take the win and have the chance to bring more Nazi-occupied territories into their union. Many US corporations were even collaborating with the Nazis, the US made carve outs to prevent factories in Nazi territories being bombed, as we already know the US profits immensely from war, and then after the war they shipped all the Nazi scientists and generals into high places in government. They weren't exactly sworn enemies. Defeating the Nazis was not as high a priority as limiting the influence of the USSR. Their participation was always cynical, which might be why it seemed "counter-productive" at times.

[–] AngryCommieKender@lemmy.world -2 points 17 hours ago* (last edited 17 hours ago)

On Dec. 3 1941, the US as a whole was quite content supplying the allies with everything they needed materially. We had told the USSR to just make tanks, we would give them everything else, including the ammunition for said tanks. Letting the USSR take a win was certainly preferable to what happened after they took a loss at the end of WWI.

I wonder what could have possibly happened on Dec. 4, 1941, that got the country to collectively say, "Fuck that. We aren't sitting by anymore."