You might note that there were many Ukrainians that signed up with the Germans; the SS had at least one division (14th Waffen Grenadier) division of them. Some Ukrainians still celebrate that division. Google "Lavrov Division" of the current Ukrainian Army, and you can read how that division still has members with "neo-Nazi" leanings, as well as their division symbols are derived from Third Reich units.That might actually be the best scenario for the Russians. Ukrainians, historically, haven't been particularly fond of Russians--one of Hitler's many strategic blunders was treating Ukrainians like Russians when they very likely would've taken Finland's route and joined the Krauts against their common enemy. It seems to me that if the Russians invade, they're more likely to end up with another Afghanistan, and there's no way they could guard the entire length of the pipeline.
If, however, they let the Ukrainian gov't fail, then start pulling strings in the shadows...
As for the last two World Wars - it was "Austria-Hungary" that kicked off the first party, and in the end, Germany paid for it. As for the second, you could almost say the French started it, as their extremely punitive Treaty of Versailles is what led to the Third Reich, their attempt to reclaim land stolen from them by the Treaty, and the collapse of their economy by the harsh reparations levied against the German government. No Treaty of Versailles, no Hitler, no Third Reich, and no WWII.