What is Putin's angle for invading Ukraine? What is he wanting to accomplish by doing so?
So when the soviet union collapsed, Ukraine, at first, had a Russia friendly ruler. So as the other Russian territories pushed away from Russia politically-- Lithuania, Estonia etc- Ukraine remained close by. Because of this, what little funds the Russians had left were poured into Ukraine because it has the most fertile soil in all of Europe. It's is the "bread basket" of Europe. The wheat fields in Ukraine are massive and incredible and the Russians needed food after the government collapse.
Fast forward a few years and the Ukrainian people decide to revolt against their leader. They called it the Orange Revolution. So Ukraine basically ousts their leadership and puts in power a Pro-Western leader.
The USSR always saw the formation of NATO and the EU as a big "fvck you" to Russia. And since Ukraine was always Russia's "little cousin", when they start expressing interest in joining NATO and the EU it was the political equivalent of when aggie left the Big 12 for the SEC (not the best example but you get where I'm going with this). Russia, who in their weakest moment, did everything they could to help Ukraine, now feels slighted and betrayed.
And the pot has been boiling ever since then. If Ukraine said "Ok, we will never join NATO and will never join the EU" then Putin would never do this. But Putin sees NATO as a threat and wants to keep a "buffer zone" between his country and NATO Europe.
Why?
Just look back in time. How many armies over the last 500 years have tried to invade Russia--- quite a few. And strategically the advantage Russia has with a buffer zone are two fold--
1. It's a looooooong mother fvcking way across Ukraine. A long way. A REALLY long way. And for NATO to move that many tanks and troops across Ukraine to mount an attack against Russia would give the Russians plenty of time to mount a defense.
2. Winter. It's fvcking cold over there. Ask the Nazis. Oh wait, you can't. All the Nazis that invaded Russia froze to death. There were 250,000 of them that didn't make it through 2 winters...... and guess what, when winter is over and spring comes, you still can't fight. Why? Mud.
There's no mud in the world like Russian and Ukrainian mud. Good luck getting tanks and trucks through that sh!t to deliver food, fuel, ammo and meds to your troops.
So the Russians sucker you into holding out over the winter, then the thaw comes and you sink into the mud and can't move. Good luck dodging fvcking bullets when both of your boots are hip deep in mud...... talk about shooting fish in a barrel. By the time the ground warms up enough and dries up enough for your tank columns to move, you have no tank columns left.
Sure, you may control the skies, but you are mired in a ground war. War isn't fought on a flat concrete surface with no line of sight obstructions.
Two oceans (our geography) protects our country.
Winter, mud and distance protects Russia.