Chamberlain appeasement policy was caused not only by fear of the great German Army, but because their fear of the strong continental alliance - France-Czechoslovakia-Soviet Union.
Really? And if Germany and the USSR together attacked Poland, why the UK and France declared war only onto Germany, and not only onto the USSR? And the answer is simple. No one (including Poland) in 1939, seen Soviet liberation of the West Ukraine and West Belarus - lands eastward of Kerzon line, temporarily occupied by Poland, as an act of war - first of all, because Poland de facto didn't exist at the start of the Russian operation, and second - because it was Poland, who cancelled Soviet-Polish non-aggression pact by attacking (allied with Germany and Hungary) Czechoslovakia.
And they didn't do it, because of what?
It would mean only start of WWIII ten years earlier - in 2014, instead of 2024.
Putin is not bluffing. And regional war is, by definition, nuclear war. And your tactical nukes have nothing to show.
They are already directly involved in the combating Russian forces within Russian pre-war territory.
And in this combat Russia would use, for starters, tactical nukes. And as NATO forces, in fact, don't have tactical nukes worth mentioning (B61 can't be seriously counted) those NATO forces would be definitely defeated.