Diminished support for the Syrian government from Iran, Hezbollah and Russia enabled opposition forces to take the initiative and seize new territory.

Syrians are generally repelled by extreme religious rhetoric. As jihadist groups came to dominate the rebellion after pro-democracy demonstrations were crushed after the first year or so of war after 2011, many Syrians either stayed neutral or sided reluctantly with the regime because they feared the murderous jihadist ideology of Islamic State.

Iran has thrown its support behind Syria's government after thousands of insurgents took control of the country's largest city of Aleppo.