drgondog
Major
Read up on Toba. The effects of shutting down sunlight for years, expelling massive quantities of SO2, ash covering global crops/rain forests/plains, etc.Yeah it would be absolutely devastating: It would have disastrous effects on weather patterns, plant and animal life and even if we invaded Russia, it'd be irrelevant.
BTW: The idea the Russians had claimed about nuking Yellowstone was that it would set in motion a positive feedback loop that would activate all volcanoes along the Pacific Rim. The thing is that Russia has a side on the Pacific Ocean which would mean they'd be pulverized too even if we didn't fire back (and we could definitely get our weapons off before theirs hit). They might as well just blow their own brains out.