The same guys who are arming Iran and providing technical assitance to their nuclear programme, no?
One school of thought is that Russia is in Iran mainly to cause us trouble, to counterbalance us.
I wonder...suppose Bush had not pushed NATO right up to the Russian border, which was a tremendous insult to the Russians, and instead offered Russia a strategic partnership...maybe Russia would not be meddling in Iran today.
But then again, maybe Russia would have taken the partnership and then expanded its influence anyway. But IMHO Bush should have at least tried to work something out.