It's slightly more than that. Russia (Putin) can't stand a successful democracy on his border, especially one that used to be in the USSR. For some reason, he ignores Estonia, Latvia, and Lithuania. But Ukraine? It's a direct threat to Putin's power if it is successful as a real democracy, if it turns toward the west. Not just because it diminishes Russia's sphere of influence, but because it shows a path that Russians could take - a path that leaves Putin not at the top of "the vertical of power".