This doesn’t look good:

Ukraine has sent in troops to clear out occupied government buildings in the city of Sloviansk, sparking a new round of violent clashes in the eastern part of the country. The fighting comes one day after President Oleksandr Turchynov announced that Kiev would move forward with “counter-terrorism” efforts in the east. Some outlets are reporting that a number of Russia separatists have been killed in clashes with Ukrainian soldiers. …

Russian President Vladimir Putin, not surprisingly, appears to be seizing on the event as justification both for the previous annexation of Crimea, and a pretext for further incursions into Ukraine. He said using the army against the Ukrainian people is “a very serious crime” that would have “consequences.” The Russian army claims they’ve been “forced” to launch news military drills along their border with Ukraine as a response.

Civil war expert James Fearon of Stanford tells Zack Beauchamp why he wouldn’t call this a “civil war”:

What we’re seeing is not so much civil war as an intervention by a very powerful neighbor who’s interested in annexation, but now there’s an interesting question as to what’s sort of path there will be towards actual annexation or will they be content with something formally short of that. The Russian Army is so strong that, relative to anything Ukraine could put up against them, I don’t see them starting a war against the Russian forces. And since that appears to be who’s there in the east, I don’t see what the fight would be.

If [Putin] extends this program further west, you could imagine the development of a terrorist or violent guerrilla movement that could someday get to civil war levels. There just isn’t much evidence right now that, at the core, this is a conflict between Ukrainians.