Russia now has 30,000 troops sitting along the border with Ukraine, and intelligence types seem to be revising their opinion of what's going on:

Troops on Russia’s border with eastern Ukraine—which exceed 30,000—are “significantly more” than what is needed for the “exercises” Russia says it has been conducting, and there is no sign the forces are making any move to return to their home bases...

The United States believes that Russia might decide to go into eastern Ukraine to establish a land bridge into Crimea.

President Obama is talking tough about NATO, but Ukraine is not part of NATO. Anyway, NATO is not what it used to be.