One of the forces that comes to mind is Russia-which-having negotiated a pipeline deal involving Kosovo,is in no mood to re-negotiate.
Actually the Kosovo & Albania pipeline deal is ours -- the projects are called AMBO and Nabucco. The Russian deal is with Serbia, proper, and its called Southstream.
But you are right in that Russia is one of the players now -- but back when all this started in the Balkans in the 1990's, Russia couldn't tie its own shoes.