russia and iran are allies. just like germany and russia were allies during WWII. russia has a large muslim problem. Iran is an islamic state and in order to keep muzzies in line, there is no better way than killing a couple of thousand at a time to “negotiate from strenth”.
Iran is a Shia Islam state. Two totally different Islamic traditions (and they fight each other more than they fight the West or Russia). Iran is also a Russian ally.