I think it's primarily military hardware and capital equipment for nuclear development. And, more than likely, nuclear delivery systems. Money and political influence. But, Russia doesn't have the military wherewith-all to project power beyond it's own borders. And, there's not an open land route between Russia and Iran available. I suppose Russia might work a deal with about three “stans” so to open a logistical land route. But, I don't think the “stans” are very fond of Russians. So, the only real threat at Russia's disposal is the nuclear option. And, I don't think even the Russians are that stupid.
Thanks for the input. Not sure I followed what you were saying here.