Turkish President Recep Tayyip Erdogan hosted his Russian and Iranian counterparts on Monday for their latest summit on Syria, vowing to work together to prevent further humanitarian crisis in the last rebel-held bastion of Idlib.
Presidents Vladimir Putin and Hassan Rouhani met Erdogan for separate talks in the Turkish capital before they all sat down for their fifth summit on the conflict since 2017.
Iran and Russia have been staunch supporters of Syrian President Bashar al-Assad, while Turkey has called for his ouster and backed opposition fighters.
But with Assad's position looking increasingly secure, Turkey's priority has shifted to preventing a mass influx of refugees from Idlib into Syria's northwest. The statements to the press were short on specifics, but Erdogan said the talks were "productive" and that they had taken "important decisions".
"We are in complete agreement in aiming for a lasting political solution for Syria's political unity and territorial integrity," he said as the summit began.
Turkey is concerned over the steady advance of Syrian forces, backed by Russian airpower, despite a series of ceasefires.
Turkey has 12 observation posts in Idlib to enforce a buffer zone agreement struck a year ago with Russia to prevent a full-scale Syrian offensive. But the posts look increasingly threatened, with one cut off from the rest of Idlib when Syrian forces advanced last month. Russian airstrikes have continued in the region despite the latest ceasefire agreed by Ankara and Moscow on August 31.
"A zone of de-escalation should not serve as a terrain for armed provocations," Putin said as the summit opened.
"We must take supplementary measures to completely destroy the terrorist menace that comes from the zone of Idlib."
The final summit statement said the three leaders were "alarmed about the risk of further deterioration of the humanitarian situation in and around (Idlib) as a result of continued escalation and agreed to take concrete steps to reduce violations."
They also said they had agreed on the composition of the long-mooted constitutional committee to oversee the next stage of a political settlement in Syria.
This was a priority for Moscow, which wants to add a political victory to its military successes, said Dareen Khalifa, senior Syria analyst at International Crisis Group.
But she told AFP that even an agreement on the committee "leaves a crux of issues unaddressed for the future of the political process including the regime's ability and willingness to undertake any kind of political reform."
High on everyone's mind at the summit was the weekend attack on Saudi oil facilities, which Washington has blamed on Tehran, deepening bilateral tensions and putting the region on the brink of further conflict.
Iran has been a crucial actor on the battlefield in Syria but has kept a lower profile in recent months. Its focus has been on countering Israeli and US involvement. "The presence of American military forces in a United Nations member and independent country such as Syria endangers its territorial integrity and national sovereignty," Rouhani said at the start of the summit.
"American forces should leave the country at once."
Iran's concerns were partly reflected in the final statement, which said attacks by Israel in Syria were "destablising" and a violation of Syrian sovereignty.
Turkey's concern about the strengthened position of Kurdish forces in northern Syria was also reflected in the statement. In a clear reference to the Kurds, it said groups trying "to create new realities on the ground" and advance "illegitimate self-rule initiatives" were not acceptable.
Turkey has repeatedly threatened to launch a cross-border offensive against Syrian Kurdish forces, which it sees as allied to Kurdish militants on its own territory. That has strained Turkey's relations with NATO ally the United States which backs the Syrian Kurds as the main fighting force against the Islamic State group (IS). The US has vowed to work with Turkey to move Kurdish forces away from its border, but Ankara says progress has so far been "cosmetic" and it could launch an operation into Syria by the end of this month.
Turkey led operations against IS in 2016 and the Kurdish People's Protection Units (YPG) militia in 2018.