You see, the Germans (and other Europeans) had killed forty million of Russian previous time. It's a quite traumatic historical experience, even if the Russians don't recognize it.
You see, from the Russian point of view there are, say, three gradations of the Ukrainians:
1. Ukrainians (Borderlanders) - just ordinary Russian people, living in the Borderland. They have their own regional features, but who doesn't?
2. Khokhols (forelocks) - Russian people who say that they are not Russian people, who invented their own "identity". Funny, but almost harmless weirdos (from the Russian point of view).
3. Banderovchi (Ukrainian Nazi Collaborants) - hired by the Western invaders mercenaries, traitors of the Russian people. They are either hired guns or rabid dogs. Both of them hardly can be responsible for their behavior. Their recruiters are. You pay money, you give them weapons - you are responsible for their behavior.