Syrian rebel faction Faylaq al-Sham, targeted by deadly Russian air strikes Monday, is one of Turkey’s main allies in Syria, and a source of mercenaries sent to Libya and Nagorno-Karabakh.

The faction was founded in March 2014, bringing together several Islamist groups fighting in the north and centre of the country as well as near Damascus.

Faylaq al-Sham is considered to be close to the Syrian branch of the Muslim Brotherhood, with some experts considering it to be its military arm.

In the northwest, it was part of the alliance called Jaish al-Fatah with jihadists from Syria’s then Al-Qaeda affiliate that overran Idlib province in the summer of 2015.

Later, it fought against the jihadists of Hayat Tahrir al-Sham — which has since renounced ties with Al-Qaeda — who now control Syria’s last major rebel bastion of Idlib.

Faylaq al-Sham’s thousands of fighters are today present in the north of the country, including in Idlib and other areas such as Afrin and Azaz controlled by Turkey’s Syrian proxies.

Faylaq al-Sham has fought alongside Turkish troops during the country’s three cross-border incursions on Syrian soil since 2016, especially against Syrian Kurdish fighters.

Nicholas Heras, of the Institute for the Study of War, said Faylaq al-Sham was likely targeted on Monday as a message to Turkish President Recep Tayyip Erdogan that there are consequences to Turkey’s wide use of Syrian rebel fighters in conflicts where Russia is also involved.

“Faylaq al-Sham is Erdogan’s favoured Syrian rebel proxy group, and it is a main recruiting agency for the Turkish leader’s foreign legion that he is deploying against Russian allies throughout the Greater Middle East, from North Africa to the Caucasus,” he said.

The Observatory says some Faylaq al-Sham combatants have individually gone to fight on the Azeri side in the Caucasus, while the faction has sent more fighters to battle in Libya on the side of the UN-recognised government.

According to the Britain-based monitor, some 18,000 pro-Ankara Syrian mercenaries have been sent to Libya since last year.

It says that, in total, more than 2,000 pro-Ankara Syrian fighters from different factions have been sent to Nagorno-Karabakh.

Monday’s strike by key regime ally Russia killed 78 fighters from Faylaq al-Sham, and wounded 90 more in training camp near the Turkish border in Idlib.

It was the second such devastating air raid by Russian aircraft to target the group, after another in September 2017 killed almost 70 members, also in Idlib.

A Russian-Turkish ceasefire deal has since early March largely stemmed a Moscow-backed regime military campaign against Idlib.

Several rounds of UN-backed peace talks have failed to end Syria’s nine-year war.

In recent years a parallel track of negotiations led by Turkey on one side, and Russia and fellow regime ally Iran on the other, have instead taken precedence.

As one of the most prominent groups of the armed opposition, representatives from Faylaq al-Sham has taken part in both.