The title of the Tsar was: "Emperor and Autocrat of all the Russias, of Moscow, Kiev, Vladimir, Novgorod!" referring to four important Russian principalities. And the Tsar, who launched the insurgency against the Tartars and united Russia was Ivan III the Great, the "gatherer of the Russian lands".
Well, the word Tsar is derived from the word Cesar; when Peter the Great married a Byzantium princess. That's a claim to the whole of the previous Roman Empire including France, UK, Turkey.. you get the picture. Europe then responed with the Crimean War, to check that Roman aspiration.
Peter I the Great expanded Russian territory to include good access to the seas of the world and its merchandise via harbours that also house a strong fleet of warships protecting the Russian sea lines of communication. There is the legendary greatest shipyard of the Soviet Union, the Black Sea Shipyard in Mykolaiv, Ukraine, up for grabs and with it all implicatins of building a native blue water navy with giant aircraft carriers.
And so back in the day Britain and France responded in the Crimean War, with 100s man-o-war destroying every Russian fortification in the Baltic and sailed towards St. Petersburg.
The current Ukrainian gouvernment is dominated by people with an ideology close to the Nazis that are often taken as neo-Nazis. Russia fought the Great Patriotic War with a loss of millions and millions of humans against the German Nazis who wanted to degrade them to subhuman serfs for a masterrace. Russians are unlikey to follow through on the fine nuance the Svoboda party tries to make between national democrats and national socialists = Nazi.
How are the Ukrainians close to being Nazies?
Besides, Nazi is a party, Facists are their political identity. Ukraine as a part of Soviet Union fought the Great Patriotic War that resisted the Fascist Invaders. National Socialists =/= Nazi; it is just a name. Is the DPRK really democratic?
These are three reasons that give whatever Russian gouvernment green light to launch HELL on Ukraine and take it with all means available, meeting resistance only in the thinly populated remotest Western parts. Economic sanctions are a joke as countermeasures. The pro arguments have the most profound roots of all things Russia consider great about their history and contain everything they want in order to be great again. Plus Putin will inevitably become Vladimir III the Great(est) (president).
The only real countermeasure would be massing NATO's armed forces on the other side of the border. As soon as we send boots on the ground in Ukraine, we will inevitably see people welcoming us with swastikas, Nazi salutes and other goodies of the Third Reich. Is NATO going to defend the Fourth Reich in the Second Cold War going hot?
I mean, history have happened before, if Britian and France was willing to go to the Crimean war to check the expansion of imperial Russia; What makes it so certain that NATO and the EU would not?
Ukraine is no Germany of the 1930s. The German Economy was equal if not bigger than the Soviet Economy; Heer's army is significantly better trained and armed than the USSR; and so is her industry, science and technology.
Thus claiming Ukraine as the Fouth Reich is rhetorical at best, Ukraine cannot lift a finger towards Moscow.
If Russia feels bold enough to launch an invasion of Ukraine, nothing is going to stop them. They know it, we know it and we all need a face saving way out. Afterwards, we can support the democratic rights of neo-Nazis in occupied Ukraine in their free speech attempts glorifying the Holocaust. There are also other Ukrainians, but we live in a world bent on conflict and for this reason black and white pictures prevail.
You can try to dehumanize the Ukrainians as Nazis, but why don't you do the same to the Russians and call them the Sucessor to Stalin's Gulags or something to that order?
And it is not that nothing could be done, the Crimean war showed it. What can Russia do if Nato decides to send 4 armour division with 4 wings of fighter and attack aircraft to buffer the eastern Ukraine; exert local control over the black sea so to starve out the russian forces there? And, sail 7 CVBG up the baltic coast?
What could the Russian do? Honestly Can russia muster a sufficient force that can take on NATO right now? especially given the dire situation of her logistic capacity.