The West was in no position to prevent it. Not that FDR minded that situation, mind . . .The US gave Stalin signal assistance, especially Studebaker trucks for mobility of the Red Army. But that was the price of keeping the USSR’s oil fields out of Hitler’s hands.
Granted that the US could have abrogated alliance with the USSR after the battle of Kursk, when the oil fields were no longer in danger - but if so, reduced Soviet pressure would have meant that the allied invasion of Normandy and into Germany would have faced German resistance from units which in fact stayed on the Ostfront.
And if you think that woulda been fun, you must have loved the Battle of the Bulge. Which Hitler launched precisely with units withdrawn from der Ostfront . . .
“Which Hitler launched precisely with units withdrawn from der Ostfront . . .”
It was a band of those eastern front types who outright murdered 84 American prisoners. Part of their defense was that this mass murder was normal in the east. Anyone think the US Army could have partnered up with this bunch of low lifes 3 months later has a screw loose. Not to even mention the camps they were soon seeing.
No, a nazi-US alliance was not in the cards. Might as well have asked the US Army in 1976 to ally with the VC/NVA to go after Pol Pot. Or ask our boys in Syria to join up with Al Qeida to go after ISIS.... Sayyyy, wait just a cotton picking minute.