Russia already had Crimea, there would have been no need for Ukraine invasion just to retain it. That makes no sense at all.
Your argument over Russian security - even taken at face value - is flawed. Russia has a historic issue with its Western Frontier. It is impossible for Russia to defend with its infrastructure due to the geography (its very flat). Russia has historically managed this by controlling other countries to create pinch points in the geography. Controlling Ukraine does no good at all in securing this border, it would need all of Eastern Europe and part of Germany to create an effective frontier that Russia could defend.
Why give me your own opinion of what is or is not a red line to the Russian? Isn't it obvious the only relevant opinion is theirs? Which
numerous Western diplomats and geopolitical strategists found and said in no uncertain terms? Then history has proved them right, and further confirmed by Bennett, Arahamiya and Stoltenberg. If you are unwilling to accept NATO expansion was the principal cause, what do you think the US would have done if the shoe was on the other foot, say if Russia were forming a military alliance with Cuba and Mexico with a view to point missiles there at the US?
I don't mean to be rude, but aren't you a living proof that democracy is doomed by showing even a perfectly intelligent person interested in politics is unable to be objective in the face of overwhelming evidence and logic? Isn't it then a bit rich criticising gammon voters' self-harm by putting Boris/Truss/Trump/Biden etc. in power, given extensive self-harm has already been done in support of this war?
Many here clearly believe they occupy the moral high ground - but what is moral about supporting the side that provoked the war, the same side that is supporting the slaughter of a thousand children a week for the past 11 weeks, after waging numerous wars with the "noble intention" of spreading democracy? The genocidal ethnic cleanser is the only democracy in the Middle East, supposedly.
I know what I said won't change a single mind, and you all think I am in the minority - but I am not. The "Global South" represents c88% of world population - they know Russia's invasion was wrong and illegal, so were Hamas' atrocities on 7th October, but since they don't get saturated by the miracles of our media's alternative reality, few are willing to criticize Russia or Hamas precisely because objectively history did not begin on 4th Feb 2022, or 7th October. They are also quietly watching our self-harm in slow motion from ringside seats.