[rainsford]

The Russian invasion of Ukraine appears to be a case where nuclear weapons made war more likely because they can embolden a comparatively weak state to be more conventionally aggressive than they otherwise would be because they can fall back on nuclear weapons if their aggression goes wrong. If Russia did not have nukes, it seems far more likely that western powers would have directly intervened in Ukraine, a version of the war Russia seems incredibly unlikely to win.

Would the threat of getting humiliatingly curb-stomped by NATO have been enough to dissuade Russia from invading? Maybe, but it would certainly have provided more of a disincentive than the current state of affairs where Russia can use the threat of nukes to keep NATO at bay. I'd bet a hypothetical nuke-less Russia would have stayed in their own borders and been content to get rich off fossil fuels. On balance, the existence of nuclear weapons probably still prevents more wars than it starts, but Russia having nukes seems like an exception to the rule.