Huh ArabKnight, first important thing: Why you define Assad a regime? He represent Syria Government. REGIME is the right term for all "syrian" (90% not syrian, but from other country) rebels which ALL are just pure terrorist rats, backed by USA, EU (mostly France and UK), Turkey and Gulf States, all puppets by Pissrael. Pissrael also helped physically ISIS terrorist and former "FSA" when they are active near on Golan Heights (in Daraa countryside) through medical treatment (also in Pissrael hospital), army supply and money. All this you can find all the evidence when the heroes of Syrian Arab Army (Assad) liberated this area of south Syria 1-2 years ago.
I follow the war, got not much interest in only first phase, start follow in 2014, a little before when Russia start intervention in Syria (2015), and I cannot explain you in short words what happened, tremendous quality of information and happened in this time until today, but I can define your reasoning incorrect:
first: read this long interview with Assad, released by SANA a few days ago, it will explain to you very clean the current and above situation of Syria-n war:
https://sana.sy/en/?p=177331
second: Iran help Assad (which represent Syria Government, which means "guarantor" of rights, law, all about "civil society") for cultural reasons, both are against Israel. With Iraq and Hezbollah, it is "axis of resistance" against "West", or in other word, Pissrael, in other word "jew" lousy culture. When your brother needs help, you go to help or preferrer to see him fall on YOUR enemy, and potentially your enemy will be more near on you if you not help? So, with or without Ali Khamenei, this is not much matter of him presence. Important guy is Qasim Soleimani, Major general, is his behind the capacity of war strategy in Syria, he is also enemy no 1 for USA and Pissrael, because he is able to face the superpowers of West, puppets of Pissrael.
third: Russia help Assad not by "friendship", but just mere own interests, for Russia it is greater damage if Syria land falls to enemy, which means basically lost him influence on Middle East and this therefore potentially a new front against Russia, weakening power to World, compared a give support to Assad to have still own control in Syria and also power to World. Just this. Jew questions is less matters for Russia, it should be strange but, thank God, Russia do for own interest than a Israel interest.
You have to start to distinguish State, a normal State and a Deep State. All of West country involved in Syria war is all from Deep State, normal people of this State don't know their own State are supporting extreme terrorist on Syria, due to controlled media and disgusted people behind of all this, all are fucking jew and despicable goyim supporting Pissrael.
The really of things is more complicated but I made an extreme summary, hope you understand now, read Assad's interview above, and keep reading SANA website. You have other question to ask?
Without our RTR, Assad is just simply dead many years ago, as Gheddafi.