Getting rid of Putin

As people watch the situation in Ukraine unfold it can be difficult to understand the policy the west is proposing. All parties in the west seem to agree that we cannot institute a no fly zone because that would pit the US against Russia and lead to WW 3. At the same time these same people say if Russia invades Estonia the West will respond and that would pit the US against Russia and start WW 3. If that is the case will NATO really honor the article 5 if it means WW 3. If they don't will Russia then move on to Latvia and Lithuania and so on down the line until Putin regains all of the countries that were part of the old Soviet Union. When Putin campaigned for re election in 2018 he said he wanted to reverse the collapse of the Soviet Union. Will the American people and other citizens of the West ever agree to go to war to defend NATO if they believe it will start WW 3? Until that belief is acceptable Russia can take over any country they please. Many say and they may be right that the only solution is to remove Putin from power but they don't say how to do it.