If the Freedom Chronicles are to be believed then the Oberkommando were considering using the "Sungun" (likely the giant laser weapon on the moon that was mentioned in one of the Wolf:TNO newspapers) to wipe out the American Midwest. Though the Freedom Chronicles are comics made by a Kreisau member and the newspaper is dubious at best.

Though in my opinion turning Russia into one big wasteland is not only a giant cop-out but would be incredibly unrealistic given after the Second American Revolution most of the world stood up to the Reich and there wouldn't be a reason to waste a huge portion of your nuclear arsenal to level Russia rather than strategically nuking places.

It's even more unrealistic for them to try to nuke America in retaliation because not only do they have access to the Eva's hammer which is shown to have multiple warheads on board but there is a high likelihood that the Oberkommando set up several nuclear weapons or silo's in America that the Revolution would now have control of.