Simmering tension between Ankara and the regime of Bashar al-Assad over the fate of Syria’s northwest Idlib province threatened to escalate on Monday, following an attack on Turkish forces that left five soldiers dead and prompted retaliation against the pro-Damascus forces.

Five Turkish military personnel were also injured in the initial attack, at an outpost in the town of Taftanaz, on the northwest outskirts of Idlib city. Video posted online showed a military helicopter transporting the wounded to a state hospital in Turkey’s Hatay province, which borders Idlib.

The confrontation came one week after Syrian forces killed eight Turks at an observation post in the rebel-held northwest province, which has been pummelled for months by the Assad regime and Russian airstrikes and artillery.

Turkish units responded by “intensively shelling” the Syrian targets, local media cited military officials as saying, without detailing casualty estimates. A monitoring group, the Syrian Observatory for Human Rights, described relentless rocket fire by Turkey and its Syrian rebel allies, on regime positions.

“The attack was retaliated against and avenged with immediate elimination of enemy targets,” Fahrettin Altun, communications director for President Recep Tayyip Erdogan, wrote on Twitter. “The war criminal who ordered this treacherous attack not only targeted Turkey but the whole international community.”

The deadly clashes between Turkish and Syrian forces in Idlib province comes as Assad’s forces, backed by Russian and Iranian fire and manpower, attempt to consolidate their hold over the country after a nine-year civil conflict which has left hundreds of thousands dead and millions displaced but ultimately leaves the Damascus regime in power.

Syrian regime bombards Idlib Show all 23 1 /23 Syrian regime bombards Idlib Syrian regime bombards Idlib Members of the Syrian Civil Defence, also known as the White Helmets, recover a wounded boy from the rubble of a building following a regime air strike on a vegetable market in Syria's last major opposition bastion of Idlib AFP via Getty Syrian regime bombards Idlib The regime air strikes killed at least nine civilians, striking bustling areas of Idlib city AFP via Getty Syrian regime bombards Idlib An injured woman waits to receive treatment at a makeshift hospital AFP via Getty Syrian regime bombards Idlib Syrian Civil Defence, also known as the White Helmets, searching through the rubble of a building AFP via Getty Syrian regime bombards Idlib A Syrian boy is evacuated AFP via Getty Syrian regime bombards Idlib A drone picture taken on January 15, 2020, shows members of the Syrian Civil Defence, also known as the White Helmets, searching through the rubble of a building at the site of a regime airstrike on Syria's last major opposition bastion of Idlib - Regime air strikes on Syria's last major opposition bastion killed at least nine civilians, striking bustling areas of Idlib city despite a fresh Russian-sponsored truce, a war monitor said. At least 20 other civilians were wounded in the raids that hit a vegetable market and repair shops in Idlib, capital of the jihadist-held province of the same name, said the Syrian Observatory for Human Rights. (Photo by Omar HAJ KADOUR / AFP) (Photo by OMAR HAJ KADOUR/AFP via Getty Images) OMAR HAJ KADOUR AFP via Getty Images Syrian regime bombards Idlib The wreckage of a car AFP via Getty Images Syrian regime bombards Idlib A Syrian boy cries as he is evacuated AFP via Getty Images Syrian regime bombards Idlib Rescuers search for survivors EPA Syrian regime bombards Idlib A drone picture taken on January 15, 2020, shows members of the Syrian Civil Defence, also known as the White Helmets, searching through the rubble of a building at the site of a regime airstrike on Syria's last major opposition bastion of Idlib - Regime air strikes on Syria's last major opposition bastion killed at least nine civilians, striking bustling areas of Idlib city despite a fresh Russian-sponsored truce, a war monitor said. At least 20 other civilians were wounded in the raids that hit a vegetable market and repair shops in Idlib, capital of the jihadist-held province of the same name, said the Syrian Observatory for Human Rights. (Photo by Omar HAJ KADOUR / AFP) (Photo by OMAR HAJ KADOUR/AFP via Getty Images) OMAR HAJ KADOUR AFP via Getty Images Syrian regime bombards Idlib A Syrian boy grimaces in pain after he was wounded in the airstrikes AP Syrian regime bombards Idlib A Syrian youth stands at the site of a regime air strike in Ariha town AFP via Getty Syrian regime bombards Idlib Rescuers search for survivors under the rubble of a collapsed building EPA Syrian regime bombards Idlib A Syrian walks on the rubble of a building following a regime air strike on Ariha town in Syria's last major opposition bastion of Idlib on January 15, 2020. - Regime air strikes on Syria's last major opposition bastion killed at least nine civilians Wednesday, striking bustling areas of Idlib city despite a fresh Russian-sponsored truce, a war monitor said. (Photo by Omar HAJ KADOUR / AFP) (Photo by OMAR HAJ KADOUR/AFP via Getty Images) OMAR HAJ KADOUR AFP via Getty Syrian regime bombards Idlib Firefighters try to extinguish flames EPA Syrian regime bombards Idlib Emergency services look for survivors AP Syrian regime bombards Idlib Emergency services look for survivors after airstrikes in the city of Idlib, Syria, Wednesday, Jan. 15, 2020. Syrian government warplanes struck a market and an industrial area Wednesday in the last territory in the hands of rebel groups in the country's northwest, killing at least 15 people, opposition activists said. (AP Photo/Ghaith Alsayed) Ghaith Alsayed AP Syrian regime bombards Idlib A boy wounded in airstrikes is treated in a hospital AP Syrian regime bombards Idlib Syrian White Helmet civil defense workers extinguish a burning car Syrian Civil Defense White Helmets via AP Syrian regime bombards Idlib A Syrian walks on the rubble of a building AFP via Getty Syrian regime bombards Idlib People walk past destruction by the government airstrikes in the town of Ariha, in Idlib province, Syria, Wednesday, Jan. 15, 2020. Syrian government warplanes struck a market and an industrial area Wednesday in the last territory in the hands of rebel groups in the country's northwest, killing at least 15 people, opposition activists said. (AP Photo/Ghaith Alsayed) Ghaith Alsayed AP Syrian regime bombards Idlib People walk past destruction by the government airstrikes in the town of Ariha, in Idlib province, Syria, Wednesday, Jan. 15, 2020. Syrian government warplanes struck a market and an industrial area Wednesday in the last territory in the hands of rebel groups in the country's northwest, killing at least 15 people, opposition activists said. (AP Photo/Ghaith Alsayed) Ghaith Alsayed AP Syrian regime bombards Idlib People look at destruction by the government airstrikes in the town of Ariha, in Idlib province, Syria, Wednesday, Jan. 15, 2020. Syrian government warplanes struck a market and an industrial area Wednesday in the last territory in the hands of rebel groups in the country's northwest, killing at least 15 people, opposition activists said. (AP Photo/Ghaith Alsayed) Ghaith Alsayed AP

The relentless Syrian regime offensive, which has allegedly targeted schools and hospitals, has prompted hundreds of thousands of civilians to flee their homes and flock to the Turkish border.

On Sunday, Syrian regime helicopters dropped barrel bombs targeting civil defence centres, clinics, a police outpost and a school in Atareb, according to the Syrian Network for Human Rights, a monitoring group. The United Nations said on Monday that more than 100,000 people in Idlib have fled their homes in the past week alone amid a cold snap that has brought temperatures to below freezing, bringing to 700,000 the number of Syrians who have been displaced in the province since 1 December.

“With this cold front we’ve had a lot of trouble addressing people’s needs,” said Amany Qaddour, Turkey-based regional director for Syria Relief and Development, an aid group. “We’ve had to move healthcare facilities. There really are not enough medical staff to treat various conditions, because the medical workers are themselves being displaced. People have virtually no protection. People are on the move and the lucky ones maybe have a tent or some structure. Others are just exposed to the elements.”

Turkey, Russia and Iran began hammering out a deal for Syria’s north as part of the so-called Astana process which began in 2017. Turkey, which serves as the main patron of Assad’s opponents, set up a dozen observation points throughout Idlib to maintain various ceasefires.

People are on the move and the lucky ones maybe have a tent or some structure. Others are just exposed to the elements. Amany Qaddour, Syria Relief and Development

During military operations called Euphrates Shield and Olive Branch, Turkey carved out zones of influence in northern and northwest Syria where it hopes to relieve domestic political pressure by resettling some refugees.

But from the beginning, Russia has given its client Syria the diplomatic and military cover to violate repeated truces meant to protect civilians.

The folding of rebel defences in Idlib and the seizure of key highways by the regime could foil those plans, flooding those areas with newly displaced people that will make them unsustainable, and potentially destabilise Turkey.

“The problem is when the Russians and Turks entered talks in 2017, Turkey’s role was always to negotiate the terms of the surrender of the opposition,” said Aaron Stein, Middle East director at the Foreign Policy Research Institute, a Washington think tank. “They’re clever enough to call it something else.”

Facing the prospect of being forced to absorb millions of Syrians escaping Idlib on top of at least 3.5 million refugees already settled in the country, Turkey finds itself backed into a corner. Talks with Russians in Ankara were continuing over the weekend. Iran’s foreign minister Mohammad Javad Zarif on Monday offered up Tehran’s “readiness to facilitate dialogue among brother neighbours Turkey and Syria.”

But Russia has also been bolstering Assad’s forces with air power and heavy military equipment, and Iranian-backed militias that once confined their activities to southern and central Syria have been reportedly taking part in the Idlib offensive.

Mr Erdogan demanded on 5 February that Syrian forces withdraw beyond Turkish observation posts by the end of the month, warning of a potential military offensive if they didn’t. But with Russian controlling the skies over much of Syria, there’s very little Turkey can do without risking the Kremlin’s ire.