I'm going to leave this part out. I don't want to deep-dive internal Russian politics. Historically Putin came to power as part of an internal clan of individuals tied to current and former leadership roles in force-wielding institutions within Russia and the USSR. They were affiliated with the gas industry the same way that some oligarchs were with certain oil companies or colored metal exports. This group came to power in '99, and stayed in power since. The exact balance between Putin and other figures in this group is murky at best, and requires extensive research. Dictatorship and authoritarianism are not synonyms, though they're close, and they can look similar from the outside. The main question there isn't whether Putin can do whatever he wants vis-a-vis Russian society, but vis-a-vis his own partners in power.
A lot is said in places about oligarchs and power. However, can you name one who is capable to putting the brakes on Putin ? I cannot see, at this time, how this war will profit RU in the long term. The economics are grim, and get worse the longer this goes on. As far as I, an outsider can see, Putin has done everything in his power to move this war forward - barring only those things which would represent a major danger to his own power (WMD, mass mobilization). Who opposes Putin ?
For that matter, who is Putin's political successor ? Putin is 71 and past the average life expectancy for RU males. If he strokes out tomorrow, who takes power, or does this degenerate in a civil war none of us wants ? There was an interesting discussion on this a few months back on the Project Owl Discord channel, but no clear answers.
NATO acted against another sovereign state in violation of the UN Charter. This was a major red flag. Russia was involved in several ethnic messes in the '90s both inside their own borders and outside. Even when the separatists were pro-Russian, Russia leaned on respecting state sovereignty, and not promoting actual independence. This was the case in Georgia, Transnestria, and Crimea. NATO acted against a sovereign state, and then supported the independence of pieces of that state. This was an obvious concern for Russia.
RU and the West have all violated the rules over time. NATO stopped the civil war in Yugoslavia. Was it worth it ?
It is not. '90s Russia and today's Russia are very different. And it's not inconceivable that Russia could face Yugoslav-style ethnic tensions in some regions of the country.
Even if you accept that RU is vulnerable in the same ways Yugoslavia was - RU has nuclear weapons. No one is going to invade RU.
It depends on the internal state of Russia. You can't tell me that there is literally no scenario where this could play out.
I am telling you there is literally no scenario where this plays out.
1) Who is going to invade ? The EU ? How many BDE can they mobilize ? 2 ?
2) How will get get the collective political will to invade ? Do you honestly think the EU can collectively get the will to invade RU ? You think Germany, in a million years, would invade RU ?
3) Who will supply this invasion ?
Add in 5 US divisions (half all our ground forces), and the math doesnt change. Not enough troops, not enough political will, not enough supplies. All of this ignores RU nuclear weapons, which I dont doubt for a second, would be used in this type of scenario.
Not going to happen. Never.Ever. There is no army in the world that has the forces and ability to sustain a massive ground war.
I quoted the parts it refers to. You claim Putin had removed Russian forces from, among others, Kaliningrad. But we've seen Kaliningrad host fewer military assets in the '90s and early '00s, and then later more assets as tensions with NATO rose. What time period are you referring to when you talk about units being removed from there?
11th Army Corps.
en.wikipedia.org
Various unit insignias have been spotted in UKR.
What happens if NATO decides Putin is an odious dictator and has the means to remove him?
I think Putin
is an odious dictator. NATO doesnt have the means. It never will.
Of course. It was a
humanitarian effort.

I think you're missing the point. NATO has the ability to do things that go well beyond simple mutual defense.
Sure it does - if the various parties can agree to
do something (other than argue). Do you actually think, given the NATO/EU political in-fighting that we see today, that the NATO forces would actually entertain the idea of invading RU ? I imagine it would be something like this:
[Supreme Leader in Charge of Destroying Russia]: Okay Europe, I need you to mobilize all your forces so we can get into a ground war in Russia
[Germany]: Are you kidding me ? Once was enough
[France]: Sorry, Im with Germany. Once was enough
[Spain]: what military ?
[England]: (raises hand): Oh ! Oh ! We have a BDE ! We can only supply it for 2 weeks though.
[Vizzini]: you forget the most important rule
Interesting. Der Spiegel says he said yes. Did he change his story? I think it's clear western politicians intended their Russian and Soviet counter-parts to believe there would be no further NATO expansion and they accomplished this goal. Then further NATO expansion occurred.
Did he change his story ? I dont know, ask him. (yes, I know hes dead). At the very least there was no treaty in this regards.
Putin said he wasnt going to invade Ukraine. RU and UKR had a treaty, which is better than a possible back-room handshake, and look how that helped UKR.
Again - a fear of NATO is a smokescreen. Putin's own actions show that he is not afraid of NATO in the slightest.
But it's not inconceivable that Russia faces major internal dissent bungled crackdowns, coupled with ethnic tensions in some regions. And let's say the west is very unhappy with how Russia handles this dissent and the ethnic tensions. Now it becomes a question of is it possible for the west to interfere?
Im pretty sure that at this point, if RU undergoes large scale internal dissention, most of the west will take the time to look smug and say "told you so", and not give another shit. An actual civil war in RU would likely be an ungodly sea of blood and destruction, capped off by the use of nuclear weapons. No one wants a slice of that.
Regardless, there is no force structure in the world that can sustain an invasion of RU.
(and, yes I know UKR took a tiny sliver of the Kursk area, but thats not what we are talking about).
If Ukraine and Georgia are NATO members, and Azerbaijan is a closer partner, suddenly inserting forces via the Caspian into Tatarstan might be a credible option, coupled with a no-fly zone in southern Russia.
(lets ignore the fact the UKR and GA arent NATO, nor will likely ever be NATO, and Azerbaijan will want no part of invading their billion-times larger neighbor)
Insert forces ?!?!? WHAT FORCES ?!?!? Two US airmobile divisions and a few Btl. of EU troops ? How the f$ck are you going to sustain 25000 troops over there, and what do you think you will accomplish in Tartarstan ? Seriously ?
again:
1) no political will
2) inadequate forces
3) inadequate supply
Never.Going.To.Happen.
It's not about NATO actively preparing to invade. It's about making such an invasion effectively impossible, regardless of circumstances.
Its impossible now. The only scenario I can forsee is if we can bring Godzilla from the deep ocean, and set him upon RU.
Whether or not RU takes over UKR doesnt change the degree of impossibility. Taking over UKR simply increases your border with NATO !
Hitler invaded RU will some ~300 divisions. The US, all in has about 10.
Why dont you lay out a Invasion of Russia scenario. What are the forces. What are the logistics, what are the goals.