There are multiple rumors about Russian forces disguised as Berkut, there are some evidences about Russian snipers here, there are videos of some military force

There are multiple rumors about Russian forces disguised as Berkut, there are some evidences about Russian snipers here, there are videos of some military forces of non-Ukrainian origin in Southern Ukraine, etc. I don't give this full credibility (usual rumors in time of unrest, perhaps), but still there's no smoke without fire.