I actually think the answer is boots on the ground and NATO troops on a permanent basis in Ukraine to contain Russian saber rattling. Problem is this, there is a definite war fatigue in the West, we had a long commitment to the war on terror for very little gain. And not just the US, the Germans, Dutch, British and Australians have made significant contributions to allied deployments in the Middle East and central Asia. France has had troops deployed actively engaging terror groups in Africa and still does.
Add to this the COVID situation, most western countries are now massively in debt as they have tried to cushion their societies through the burden of this pandemic, spending blood and treasure fighting in Russia would not be high on anyone's list of priorities. The Chinese cheer it on from the side-lines knowing that continued blood and treasure spent on conflicts will continue to strengthen their position against both the Russians and the west as a whole.
Now lets look at the prospect of war with Russia. For the first time arguably since the second world war the west will not be fighting an asymmetrical conflict, unlike fighting Vietnamese guerrillas in the jungle, or terrorists and 3rd world armies in the middle east they will now be fighting a modern, professional, equipped, motivated enemy. The west will not be able to deploy their air power as effectively as in any other recent conflict, Russian SAM capacity particularly at lower altitude will cause significant losses. The field craft of Russian soldiers will mean that ground targets will be significantly harder to spot and target. That said if NATO had mobilised they should have been able to put at least 100,000 European soldiers into the field, the Poles should commit everything they have to defend Ukraine and the US should have matched that commitment. Had there been 300,000 NATO troops in the theatre, maybe the Russians would have genuinely come to the table. Ukraine will be carved up like Czechoslovakia and Poland was by Hitler.
