I dont understand why Russia keeps popping up in this conversation as a possible military ally of Iran. Its true that Russians make harsh statements all the time on their foreign policy.But the truth behind that is that those statements are infact aimed to Russian domestic policy. Its just a way of Russian politics to feed the sense of strength and honor of Russians and get some cheap points in the process. If Russia would really be hostile towards the West it would have escalated already few years back when the Baltic states entered NATO.At the moment there are NATO planes covering for example the Airspace of Estonia,only couple hundred kilometers from St.Petersburg.Back then the West entered really in the area that Russia thinks its part of its sphere of influence.And they didnt reacted anyway in the end.
If Iran would be put on trade embargo or attacked,it would only benefit the Russia,becouse as one of the biggest countries in Oil business the increase of Oil prizes would just increase her profits. If you look at any reacent conflicts,some Russian politics always give very hard statements,but like i sayed in the start of the post,in the end it doesnt have anything to do with her foreign politics.