Just to stop derailing the thread, a few thoughts about the discussion in the last couple of pages and then I won't mention them again:
-Ukraine is not a threat to Russia's existence, more like the other way round. Ukraine has been independent for about 30 years and has been invaded by Russia 3 times (Crimea, Donetsk-Lugantsk, and now the whole country).
-NATO is not forcing anyone to join. If anything, it has made the process of joining really difficult for other countries. Since 2009 only two have done it.
-NATO nor anyone will invade Russia as it now has nukes. The aggressor of the last 2 times was defeated, occupied, downsized its army, doesn't have nukes and depends on trading with Russia (although the last three are about to change due to Putin's decission to invade).
-Russia tends to invade a lot more often than be invaded. However, it appears to show a tendency to invade and then be military embarrased every 40 to 50 years, and it tends to happen against smaller powers everytime. First the french, then the turks, the japanese, the finnish, the afgans and now Ukraine.
-Esentially, Russia's status as a great power now seems to depend on A) its nuclear reserves and B) its non-renewable resources (Oil and Gas). Whatever the result of the war is, Russia's situation in both is now weaker: invading countries that got rid of their nukes tends to dissuade other countries of doing the same (and encouraging others to get them), making Russia's nukes less relevant in the long term. And, of course, the invasion also accelerated the end of the EU's dependency on Russian oil and gas.
-The US actions in other parts of the world are no excuse for Russia's actions. As a matter of fact, the US is still paying the price for most of the wrong decissions it made there. But there's a different thread for that.