The Last Stand for Pro-Russian Forces in Eastern Ukraine?

A re-vitalized Ukrainian Army is on the march against pro-Russian separatists in Eastern Ukrainian cities. Russian President Putin has not responded to calls for help from rebels he was encouraging just a few weeks ago. Why not? Is protracted urban warfare inevitable? Is there any prospect for peace?

After re-taking Sloviansk in the eastern part of his country this weekend, Ukrainian President Petro Poroshenko said pro-Russian rebels were making their “last stand.” But the rebels show no signs of making it easy: they’re concentrating their forces in Donetsk, and they’ve blown up three bridges leading into that city of one million people.