Russian Special Forces are some of the best in the world. Just ask the Terrorists who took over a theater a while back.
Not to rain on the Spetznaz parade, but SOF units con't hold a country the size of the Ukraine, no matter how good they are. Chechnya showed that SOF can spank people all day long, but if you don't have a competent regular Army to back you up, you'll never make any progress.
Russia don't have a competent regular Army. Trying to invade the Ukraine at this point could make Chechnya look like a stroll through the park. If there is widespread resistance or civil war, the Russians would be insane to stick their heads into it.