Sevastopol has been a Russian navy base since about the 1790s. The British fought the Crimean War there in the mid-1800s, the goal of that war was to invade and drive the Russians out of Crimea. He didn’t invade and steal anything. A party literally inspired and owing loyalty to the Third Reich took over Ukraine. Their clear intent was to turn that 200 plus your navy base over to Nato. That would be similar to us turning over Norfolk Navy Base. This wasn’t Putin invading Ukraine, this was a provoked reaction as NATO grabbed its final nation in it’s drive east to put them literally on the Russian border. And think about one other thing, seizing Kiev in a coup doesn’t give you the right to rule all of Ukraine, anymore than a pussy hat, BLM, antifa mob seizing DC would give them the right to rule all of the United States. When you seize the government in a coup, everybody else in the territory has the same right to grab what they can. And for the same exact reasons. A coup is outside the law.
You’re making an argument for a civil war in Ukraine and that is not a defense for an act of naked aggression by Russia making a cowardly sneak attack into the country (Little Green Men) and then annexing it after a BS ‘election’.