Syria insurgency: Who are the Hayat Tahrir Al Sham rebels trying to topple Assad?

Insurgents have taken large parts of the country and have Damascus in their sights

People inspects a camp for internally displaced people destroyed during an air strike near the village of Harbnush, north of Idlib, Syria. AP

People mourn relatives killed in a reported Syrian regime air strike on Wadi Khaled camp at the SAMS Hospital in Maarat Misrin, a town in Syria's northern Idlib governorate. AFP

Displaced Syrian Kurds ride in the back of a vehicle loaded with belongings on the Aleppo-Raqqa motorway to flee areas on the outskirts of the northern city of Aleppo after they were seized by Islamist-led rebels. AFP

Medics inspect the damaged Ibn Sina Hospital following a Russian air strike, in Idlib, northern Syria. EPA

Militants gather at the Nayrab military airport, in the northern Syrian city of Aleppo. AFP

Syrian military aircraft are among the equipment at the airport. Militants have taken control of large parts of Aleppo. AFP

A militant patrols outside the airport. The offensive has resulted in Russian air strikes on Syria. AFP

Fighters stand guard outside the northern Syrian town of Tal Rifat. AFP

A member of the Syrian White Helmet civil defence helps carry a victim of Syrian government attacks on Idlib city. AP

Anti-government fighters reach the motorway near the northern Syrian town of Azaz. AFP

Anti-government fighters celebrate as they take over the northern Syrian town of Tal Rifaat. AFP

Anti-government fighters swept into the city of Aleppo, east of Idlib province. AFP

The Syrian army said dozens of its soldiers had been killed in the attack on Aleppo. AFP

Smoke billows in the aftermath of what the White Helmets say is a strike, in Idlib, Syria. Reuters

Syria's President Bashar Al Assad meets Iran's Foreign Minister Abbas Araghchi, in Damascus. Reuters

A nurse attends to an injured woman in Idlib, Syria. Government air strikes in Idlib killed at least three civilians, including two children, and wounded 11 others, said the Syrian Civil Defence. AP

Anti-government fighters take a position near the northern Syrian town of Tal Rifaat. AFP

Anti-government fighters ride a motorcycle in the northern Syrian town of Tal Rifaat. AFP

People cross an anti-government checkpoint as they return to the town of Saraqib in the eastern part of Idlib province. AFP

Syrian opposition fighters seize abandoned Syrian army ammunition in the town of Khan Assubul, Syria, southwest of Aleppo. AP

Live updates: Follow the latest on the Syrian rebel advance

Syrian rebels led by Hayat Tahrir Al Sham are closing in on the central city of Homs and have Damascus in their sights, posing a significant challenge to President Bashar Al Assad's government.

Their offensive, which has altered the trajectory of Syria's 13-year civil war, is in its second week. Already the main cities of Hama and Aleppo have fallen to Hayat Tahrir Al Sham, a former affiliate of Al Qaeda listed as a foreign terrorist organisation by the US in May 2014. Turkish proxies combined under a formation called the Syrian National Army are also taking part.

The rebel advance has altered lines of control in Syria agreed to by international powers over the past decade. It has strengthened the position of Ankara compared with Russia, Iran and the US, each of which have their own zones of control, manned by proxy militias.

Who is leading the rebel offensive?

The rebels are being led by Hayat Tahrir. It is mainly made up of groups from former jihadist organisation Jabhat Al Nusra, which was linked to Al Qaeda. It broke those ties with Al Qaeda in 2016 and rebranded itself as Hayat Tahrir Al Sham, after a purge undertaken by the group's leader Ahmad Al Shara. He is now using his real name, instead of his nom de guerre Abu Mohammed Al Jolani, as part of an effort to project moderation.

The UN and countries including Russia and Turkey have long designated Hayat Tahrir as a terrorist organisation. Al Jolani previously participated in an Iraqi insurgency against the US as a member of a group that eventually became ISIS. He then led the Syrian branch of Al Qaeda in 2011, in the early years of the civil war.

Hayat Tahrir is considered to have played a significant role in the Syrian civil war, and there are doubts over whether it has shed its Al Qaeda past and extreme ideologies.

Who are the other players?

The rebel groups include factions supported by different regional and local powers, making Syria one of the most complex front lines in the Middle East.

Another battle front elsewhere in the country is between the Turkey-backed Syrian National Army and the Syrian Democratic Forces (SDF), a US-backed group dominated by the People's Defence Units (YPG) and militiamen linked to the Kurdistan Workers' Party (PKK), a group that has waged a decades-long insurgency in Turkey.

The SDF played a major role on the ground in the US-led war against ISIS in north-eastern Syria, where Washington has about 900 troops.

Who supports the Syrian government?

Russia has been a staunch supporter of Mr Al Assad and has launched air strikes against rebel forces during the civil war. Russian warplanes have been critical for the Syrian army and its pro-Iranian militias in winning back territory. Mr Al Assad has vowed that Syria will continue “to defend its stability and territorial integrity” but he has not appeared in public since losing parts of the country last week.

Iran is also a close ally and backer of Mr Al Assad, with proxies such as Hezbollah playing a crucial role in the conflict. Iranian Foreign Minister Abbas Araghchi met Mr Al Assad in Damascus on Sunday and said Tehran would “firmly support the Syrian government and army”. But there has been no sign of any significant Iranian intervention.

Why is the timing of the offensive crucial?

The rebels chose to launch the insurgency when Mr Al Assad’s allies were either weakened or occupied with other conflicts. The offensive began soon after a ceasefire was reached between Israel and Hezbollah in Lebanon. But Israel's assault on Lebanon has weakened Hezbollah and put Iran on the defensive.

Russia has focused military resources in Ukraine, where war has been raging for more than two years.

“Keep in mind that, for many years, the Syrian government has been engaged in a civil war backed by three main players, Iran, Russia and Hezbollah,” US National Security Adviser Jake Sullivan said on Sunday. “All three of those players have been distracted and weakened by conflicts elsewhere.”

The Syrian civil war started after authorities used deadly force to suppress a peaceful, pro-democracy movement that started in March 2011. At least 300,000 people have been killed and 14 million have fled their homes since 2011, according to the UN. More than 7.2 million Syrians remain internally displaced.

What began 13 years ago as pro-democracy protests against the government of Mr Al Assad eventually grew into a nationwide armed rebellion involving a coalition of army defectors and religious groups.

In 2020, Russia and Turkey agreed to a ceasefire in 2020 in northern Syria, which had lessened the violence until the latest offensive.