BEIRUT (AP) — When the presidents of Russia, Turkey and Iran meet Friday in Tehran, all eyes will be on their diplomacy reaching a last-minute deal to avert a bloodbath in Idlib, Syria’s crowded northwestern province and last opposition stronghold.

The three leaders, whose nations are all under U.S. sanctions, have an interest in working together to contain a potentially catastrophic offensive by President Bashar Assad’s forces to recapture the province, but Idlib is complicated and they have little common ground when it comes to Syria.

The province and surrounding area is home to about 3 million people — nearly half of them civilians displaced from other parts of Syria — but also an estimated 10,000 hard-core fighters, including al-Qaida-linked militants.

For Russia and Iran, both allies of the Syrian government, retaking Idlib is crucial to complete what they see as a military victory in Syria’s civil war after Syrian troops recaptured nearly all other major towns and cities, largely defeating the rebellion against Assad.