Ukraine

Everyone looses. I'm extremely afraid of that scenario, but there is a non null probability of it happening. Meddling within the confines of the Kremlin intelligentsia can bring that kind of result but still remain necessary to achieve peace fast.

A nuclear war isn't a war: it's the end of it. France would be the one initiating it. They have a quite brutal doctrine: There is only one person to decide and validate the launch, no warning to be given (except if it's troops amassing, then a 35Kton nuke is used on the massed troops to serve as a warning) , and no second wave, all weapons are fired in one wave, then pray. France is small compared to the US, Russia or China, their strategy is to tell those bigger armies that if they attack France, to expect to lose large swath of their civilian population. The French nukes are not targeted towards army bases or nuclear launch sites but population centres only, for that reason.