The swift collapse of Syria’s regime brings a humiliating end to Russia’s and Iran’s sway and opens the door for greater Turkish influence. But the Islamist movement that seized power has yet to show its full intentions.

China quietly aligned with al-Assad through UNSC vetoes, but has not been directly involved like Iran or Russia.

The Russian military sites in Syria include a naval port on the Mediterranean Sea to berth submarines and an airfield to project power across the Middle East and Africa. But after rebels ousted Kremlin-backed President Bashar al-Assad, the future of these installations is uncertain.

Najem al-Moussa was delighted when news of Syrian President Bashar al-Assad's overthrow first beamed from the television in his tiny Athens apartment. Then came a dreaded thought: what if Assad's fall meant he and his family would be forced to return to the devastated country they had fled nine years before?

Rebel forces led by Hayat Tahrir al-Sham said they took control of Deir al-Zour in eastern Syria. Israel said its extensive strikes were to prevent a future attack.

Assad fled to Moscow as opposition forces advance towards Damascus. Sources say Russian intelligence agents organized the escape, flying Assad out of a base in Syria before the aircraft's transponder was turned off to avoid being tracked.

NBC News' Richard Engel reports from inside one of Syria's most notorious prisons, Saydnaya military prison nicknamed "the human slaughterhouse." Thousands of people in Syria have rushed to the country's prisons after the fall of the Assad regime searching for any trace of loved ones they feared had disappeared into their unseen depths.