This assertion is simply false. Russia lived with an independent Ukraine for 21 years before it started wars of territorial aggression. The only thing threatened by an independent Ukraine are inflated Russian egos.
That is your subjective opinion. The encroachment of NATO attempting to push right up to the Russian border is what started this existential threat to Russia. Especially when our American politicians made it clear they were a threat. You have seen the evidence multiple times but refuse to consider it because of your bias and hatred of all things Russian.
Why don't you allow Russia to determine what they feel is a threat?
When I was a kid and my brother started building a fallout shelter, we sure felt that Russian missiles in Cuba was a threat. They were 90 miles away from us. I cannot imagine what a threat is it to Russia to think that NATO could be right on their border. You warmongers are insane.
Because, following the fundamental presupposition of MAD, I assume there's a basic rationality to Russian actions. That basic rationality means the Russians observed how the NATO accession of former Warsaw Pact members was dragged out and was not followed by moving any permanent US bases east of the former West Germany and that all NATO members substantially scaled back their militaries starting in the late 90s. Ergo, no rational agent would assume NATO is prepared for (let alone actually preparing) to attack Russia.
In fact, the hesitancy in accession and the serious drawdown of military forces probably encouraged Russian aggression in Europe, not to mention the nearly non-existent responses to Russian aggression in 2008 - 2014.
... we sure felt that Russian missiles in Cuba was a threat.
Get back to me when we install nukes in Ukraine. The fact is that Russia violated the INF treaty by moving Iskanders into Kaliningrad and the Conventional Forces in Europe Treaty by building up its armored forces in Western Russia.
You have constructed a mythological world where Russia is the victim and the West is the aggressor.