They definitely don't want to have a higher casualty rate than Ukraine. But, a circumstance like that may perhaps make them more willing to use nuclear weapons. I doubt they would as that would grant them no long-term benefits. Not to mention that radiation spread would be so vast that they would infuriate neighboring European countries. That would only incentivize them unite against them. But... I can only guess. I know that they are not afraid to launch nukes. They have threatened countries with nuclear weapons much more than people believe. Honestly, there doesn't seem to be anywhere near enough financial transparency to conceive an accurate estimate of who will suffer more. Personally, I believe the U.S. But, who knows? They're all insane!