The Ukrainians are correct in their assessment. Photos have been shown of known GRU and Spetznaz troops seen in Crimea now present in Eastern Ukraine, and many of their agents have been arrested, along with communications intercepted. Also, it is unlikely that home grown rebels are able to launch a coordinated assault against multiple targets all at the same time, all along an important invasion route for Russia. The Useful Idiots here are a little too trusting of their communist overlords in Moscow. Anyone who doesn’t understand what the Russians are doing in Ukraine is an idiot.
And anyone who doesn't understand what the US and EU are doing in the Ukraine is an idiot.
But, it takes a really, really, special kind of idiot to think the Russians are the only ones double-dealing and murdering in the Ukraine.