Beamr :-
However, the start point of discussion was that Russia uses a WMD on Ukrainian soil.
I think that the starting point was that Putin might be tempted to use a nuclear weapon (location unknown). My position is that nothing has changed since the Cold War (with all due respect to L50) concerning Russia (nee the USSR) and NATO (aka the West). MAD still applies. MAD kept the lid on the bucket throughout the Cold War and has done so ever since. If such a strike is delivered by Russia it needs to be made clear that it will be met with retaliation against Russia in the same way. That is the only way to ensure that Putin resists such a temptation. Any other fudge such as reverting to NATO rapid response forces will lead to the very WWIII that Nutloose was wrongly accused of enabling. The West shelters under the nuclear umbrella of the USA, the UK, and France. If NATO cannot threaten retaliation as I describe (if Article 5 does not apply) then the nuclear powers could do so jointly (or even individually if necessary). The priority is to prevent Putin going for the button by threatening that we will do likewise. Like any threat it must be sincerely meant, just as it was in the Cold War. It kept the peace then and it can enable it still.
Sue Vetements, Hitler should have been stopped the moment he marched into the Saarland, let alone Austria and the Sudetenland. declaring war on him only when he ran out of German speakers to 'liberate' was far too late. Your case seems to be that Chamberlain enabled the UK to survive at the cost of the rest of Europe being enslaved by him. It would have perhaps been far better if the Allies had sorted him out long before, instead of allowing him to plunder the bullion reserves of all the occupied countries and all their armaments. I only make the point as Putin seems to be taking his cue from Hitler by substituting Russian speakers instead. He needs to be stopped now. That is why we must support Ukraine to the hilt.