If Russia wants eastern Ukraine, more and more it looks like they'll have to invade rather than rely on their Spetsnaz to capture it the way they took Crimea. The reason is that there are far fewer fools in eastern Ukraine who want to break into the prison that is Putin's Russia:
Donetsk, one of the largest cities in eastern Ukraine, is missing one element that proved vital to the success of the Kiev protests in toppling Ukraine's pro-Russian president: people. ...
A recent poll showed that only about 28% of people in the Donetsk region want to become part of Russia. Just 18% supported the seizure of the regional assembly, according to the survey, which the Kiev International Institute of Sociology, one of the country's most respected, independent pollsters, conducted from April 8-16.
Russia has fans there, to be sure. The like trade. They have family in Russia. But be part of Russia? No thank you, it seems.
Sure, Russian agents can rent a mob and import some loud talkers, but when the paycheck is gone, the protesters are mostly gone. True Putin believers are scarce on the ground.
Does Russia really want to test their military in taking an area this large? They might pull it off. But they might not. And even if they win, the Russians might lose that aura of competence that the Crimea operation lets Putin brag about.
