I don’t think the Russians will do anything beyond threats. Their hands are full in Ukraine. Their military is weak. The only thing they have to offer is nuclear war and they are not stupid enough to do that over Iran.
Iran is on its own. The days of US appeasement giving them pallets of cash are over. The days of massive air strikes are here. There’s not a damn thing they can do about it.
They can give them new SAM batteries.