While there are obviously plenty of Russian "volunteers" and "advisors" in the sepratist held areas the area where this new front is opened and these Russians are taken prisoner is a whole different game, its the coastal road from the Russian border through the strategic important harbour maripol.
This happens to be also the only land road from Russia to the Crimea.
I think its pretty obvious this is the actual Russian army invading the Ukraine, which is imperialism plain ans simple.
The mind is its own place, and in itself Can make a Heaven of Hell, a Hell of Heaven. What matter where, if I be still the same, And what I should be, all but less than he Whom thunder hath made greater?
Here at least We shall be free