Poor Ukraine - so far the western powers have taken no effective steps to curb Russian aggression against this unfortunate non-NATO member. The U.S. and Europe are using that fact as an excuse to avoid military conflict with Russia, which clearly has plans beyond the Crimean Peninsula. Reports indicate Russia is planning to open a route through Ukraine towards Moldova and is also building up troops near other former Soviet nations in the Baltics.
While this is all disturbing, I would call Russia's bluff. If NATO sends troops to support Ukraine, Russia isn't foolish enough to resort to what we feared during the cold war - atom bombs and nukes, etc. But maybe it would put Putin in his place.