The revolution turned into civil war, and then turned into a proxy world war fought by the parties to the conflict on behalf of the major powers. All of the above caused only a small fraction of the damage. Finally, Russia and America intervened directly to test their new weapons, which caused massive destruction, with bombs being used just before the nuclear bomb.
This is RBK500 bomb that Russia tests it on top of Aleppo 22–06–2016 (note: photo captured at midnight)
