For Russia and Iran- who have been both allies of the Syrian government ever since the war broke out in Syria during the Arab Spring - reclaiming Idlib is vital to complete what they perceive as a military victory in Syrian conflict after Syrian troops recaptured almost all other prominent areas, largely quelling the rebellion against Assad. Hence, five months after he said he wanted America "to get out" of Syria, Trump has now agreed to a major escalation of USA action there.
Rouhani's criticism of the United States was echoed by Turkish President Erdogan who stated that Turkey is "deeply annoyed by USA supporting a terrorist organisation in Syria". The province is home to some three million people - around half of them displaced from other parts of the country, according to the United Nations.
When the presidents of Russia, Turkey and Iran meet in Tehran Friday, Sept. 7, all eyes will be on their diplomacy averting a bloodbath in Idlib, Syria's crowded northwestern province and last opposition stronghold.
De Mistura cited press reports indicating that Syria has set a September 10 deadline for finding a solution before it begins an all-out offensive on the province.
In regaining control over other parts of Syria in the past year, Russian-brokered surrender deals offered safe passage for tens of thousands of rebels and their families to Idlib, which is why the province became the last bastion of the armed resistance.
Early on Friday, a series of airstrikes struck villages in southwest Idlib, targeting insurgent posts and killing a fighter, said Rami Abdurrahman, the head of the Britain-based Syrian Observatory for Human Rights.
Seized from government forces in 2015, Idlib and surrounding areas form the last major swath of territory still in rebel hands.
The leaders will hold a news conference after the summit.
The Syrian military has been sending reinforcements to the area for more than a month, and Russian Federation has ramped up its rhetoric. Now the goal is getting Iranian forces to go, even if that sets us up for direct conflict with not just Iran but Russian Federation.
At the same time, the Assad regime has a history of trading with the terror group", Treasury Secretary Steven MnuchinSteven Terner MnuchinTurkey's Erdoğan: "United States behaving like "wild wolves" amid sanctions Senate delays Amazon hearing pending Postal Service review: "report Trump moves toward public report on Postal Service overhaul by year's end MORE said in a statement.
But he stressed that there are some 2.9 million civilians in the province - including about a million children who "are not terrorists". Syrian government forces resumed shelling of rebels there.
Russia, which has been building up forces in the region, said it's only targeting al-Qaeda fighters, and accused the US of preparing to fake a chemical attack to justify new intervention. "You add to that, if you use chemical weapons, or create refugee flows or attack innocent civilians", and "the consequences of that are that we will shift our positions and use all of our tools to make it clear that we'll have to find ways to achieve our goals that are less reliant on the goodwill of the Russians".
"Let's f-king kill him!"
Any new flood of refugees toward Turkey would come at a time when Ankara is "vulnerable", he told AFP, adding it would be a "huge new burden on Turkey and would overwhelm its humanitarian capacities".