Russia hasn't got a long range OTH radar which covers the region. They do have a newer coastal OTH, "Sunflower", but only back in Russia and not covering the area. Even if they had its VHF band and eminently jammable.
Direct identification is of course not possible, but simply excluding "friends" we get "foe".
I did a tour based at 280SU in Cyprus back in the day - I wish you luck. Ignoring all the air traffic talking to Nicosia, Tel Aviv etc there are many many more operating autonomously talking to nobody doing various surveillance tasks - none of whom could arbitrarily designated as a foe.