The presidents of Turkey, Russia and Iran will meet on Friday in Tehran to discuss the war in Syria, with all eyes on a possible regime military offensive to retake the last opposition and rebel-held bastion of Idlib.
The summit between Turkish President Recep Tayyip Erdogan, Russian President Vladimir Putin and Iranian President Hassan Rouhani may determine whether diplomacy halts any military action.
"The Tehran summit can produce peace and reconciliation in Syria or it can deepen the mess created by endless bouts of violence mainly instigated by the Assad regime," Ilnur Cevik, a senior adviser to Erdogan, wrote in the Daily Sabah newspaper.
Northwestern Idlib province and surrounding areas are home to about three million people – nearly half of them civilians displaced from other parts of Syria. That also includes an estimated 10,000 militants, including Al Qaeda-linked militants.
But each nation has its own interests in the years-long war in Syria.
TRT World's Melinda Nucifora has more.
International powers in Syria
Iran wants to keep its foothold in the Mediterranean nation neighbouring Israel and Lebanon.
Turkey, which backed opposition forces against Syrian regime leader Bashar al Assad, fears a flood of refugees fleeing a military offensive and destabilising areas it now holds in Syria.
And Russia wants to maintain its regional presence to fill the vacuum left by America's long uncertainty about what it wants in the conflict.
For Russia and Iran, both allies of the Syrian regime, retaking Idlib is crucial to complete what they see as a military victory in Syria's war after the regime forces recaptured nearly all other major towns and cities, largely defeating the rebellion against Assad.
A bloody offensive that creates a massive wave of death and displacement, however, runs counter to their narrative that the situation in Syria is normalising, and could hurt Russia's longer-term efforts to encourage the return of refugees and get Western countries to invest in Syria's postwar reconstruction.
TRT World's Melinda Nucifora and Lucy Taylor report.
The streets of Tehran were quiet on Friday, the second day of the Iranian weekend. The country's state-run IRNA news agency described the summit as potentially offering an "agreement on peace and security" in Syria.
A former Iranian diplomat, Ali Akbar Farazi, told IRNA the summit shows that solving regional issues "in a fair way that agrees with the interests of all sides" remains important for the three nations.
Witnesses: warplanes strike Idlib
Activists and residents say warplanes struck areas on the southern edge of Idlib province on Friday, killing one and causing loud explosions and large plumes of smoke.
Rami Abdurrahman, the head of the Britain-based Syrian Observatory for Human Rights, said a series of air strikes struck a few villages in southwest Idlib and along the borders with the adjacent Hama province, targeting rebel posts and killing a fighter.
Abdurrahman said suspected Russian warplanes carried out the air strikes, which came just hours ahead of the Tehran summit.
Impacts of possible Idlib assault
For Turkey, the stakes couldn't be higher. Turkey already hosts 3.5 million Syrian refugees and has sealed its borders to newcomers.
It has also created border security zones in northern Syria and has several hundred troops deployed at 12 observation posts in Idlib.
A regime assault creates a nightmare scenario of potentially hundreds of thousands of people, including militants, fleeing toward its border and destabilising towns and cities in northern Syria under its control.
Turkey also doesn't want to see another YPG/PKK-controlled area rise along its border, as it already faces in northern Iraq.
Cevik, a senior adviser to Erdogan, also didn't pull any punches in his piece in the Daily Sabah, saying: "Assad bolstered by Iran's land assets and Russian air power and his use of chemical weapons has punched his way into opposition strongholds and hence massive gains for the Damascus regime.
"You still need moderate opposition groups who represent the Sunni suffering masses in Syria to achieve a viable political solution and durable peace in this country," he wrote. "Iran and Russia are the fighting forces in Syria and have brought blood and tears."
"No military solution"
All three nations face sanctions from the US under the administration of President Donald Trump. While America has some 2,000 troops and outposts in Syria, Trump has said he wants to pull those forces out.
America's ambassador to the UN, Nikki Haley, has warned any military offensive in Idlib "would be a reckless escalation."
The US will chair a UN Security Council meeting Friday about the possible offensive.
"There is no military solution to the Syrian conflict," Haley said in a statement Wednesday. "Assad's brutal regime — backed by Russia and Iran — cannot continue to attack and terrorise Syria's citizens."