WHAT'S GOING ON IN SYRIA? EVERYTHING YOU NEED TO KNOW ABOUT U.S., RUSSIA, TURKEY AND IRAN'S ROLE IN IDLIB

A seven-year civil war between the Syrian government and an Islamist-led insurgency has come down to a single province under rebels and jihadi control in the country's northwest, but the stakes may be higher than ever for world powers invested in the conflict.

Russia and Iran have helped Syrian President Bashar al-Assad regain most of the country, but Turkey and a number of Western powers have urged the Syrian leader and his allies not to move in on the northwestern province of Idlib, which is dominated by the Al-Qaeda-linked coalition of Hayat Tahrir al-Sham and hosts an inflated population of up to 3 million people. The United States has gone so far as to threaten military action, especially in the event it suspects the Syrian government of using chemical weapons, while Russia has claimed Western governments were conspiring with militants to stage such an attack.

A deal struck Monday by Russia and Turkey appears to have stalled any sort of imminent Syrian military attack on Idlib, but tensions remain high in the region, especially after an Israeli air raid on a suspected weapons depot in nearby Latakia province resulted in the accidental downing of one of Russia's surveillance planes by allied Syrian anti-aircraft fire.

With Moscow and Ankara attempting to begin implementing Saturday their agreement on Idlib and a new score of casualties threatening to upset Russia's careful balance of ties between arch-foes Iran and Israel, here's where the top international players in Syria stand.