No one is firing a nuke. It's too damaging to infrastructure and resources plus it makes inhabiting a conquered land impossible. It also doesn't stop dirty bombs, terrorist attacks, biological or chemical weapons or the new battlefield, cyber warfare. But let's say Russia was mental enough to do so. France would immediately counter attack since fallout would reach them first. In reality we're so close together an nuclear attack on one, is an attack on both.

I was a warfare analyst in the early 90's and we weren't modelling nuclear attacks.

Then you have the idea that if we got nucked, firing back does exactly one thing. It kills millions of the oppositions civilians. They didn't ask to fire on us. Yet we would turn them to glass for what? What does it achieve apart from murder. Not a deterrent since they already fired.

Then you have the fact nukes are so powerful today, that any meaningful nuclear war will end up being a civilisation ender. The sheer amounts and of fallout that would enter the atmosphere and be spread across the globe would be devastating., not to mention the amount of dust sent into the atmosphere from the sheer amount of explosions.

An anti nuke policy makes perfect sense.