The involvement of armed groups that are not bound by the goals of the Syrian revolution, a year and a half after it erupted, displaced large numbers of Syrians as well. This was both on account of regime bombardment of the areas these groups seized, or on account of the actions of some of them.
Russia’s military intervention in Syria is the only direct military intervention there by a state from outside the region. Iran was there first, but its intervention took different forms. No state, be it Arab or foreign, has sent experts and fighters against the Syrian regime – direct intervention by foreign states has worked exclusively for the benefit of Assad’s regime.