Ukrainian nationalism threatens the Russian people? How? You think Ukraine is going to march on Moscow? (Let us note very carefully who invaded whom here.)
What's actually happening is ethnic Russians in Ukraine getting a taste of non-Putin flavored government which would spill over into Russia. The battle here is not over some land or some resources. Putin does not want the example of an EU Ukraine to serve as a goal for his own people. An orange revolution in Moscow is what's keeping the geriatric clown up at night. This is what it wants removed. This is the actual translation of 'Ukrainian nationalism threatening Russia'. A free, prosperous, democratic Ukraine would inspire Russians to want the same thing at home. Just look at what the Russian soldiers are looting. It's very similar to some backwards iron curtain peasants suddenly ending up in Paris.