The rebels' rapid advance in the last days had reignited a years-long war that had begun in 2011 when Assad repressed anti-government protests but which had become largely dormant.

Here is a recap of their lightning offensive:

- November 27 -

Jihadists launch a surprise attack on the Syrian army in the northern province of Aleppo, sparking clashes that kill more than 130 people in 24 hours, according to war monitor Syrian Observatory for Human Rights.

The attack is launched by Hayat Tahrir al-Sham (HTS) -- which controls much of the northwest Idlib area and slivers of neighbouring Aleppo, Hama and Latakia provinces -- and its allied factions.

- November 28 -

The offensive by HTS comes during a sensitive time for Syria and the region, with a fragile ceasefire between Hezbollah and Israel taking effect in neighbouring Lebanon.

Rebels also cut the highway linking Aleppo to Syria's capital Damascus.

- November 29, 30 -

Jihadists shell government-held Aleppo and enter the northern city in a blitz assault against forces of the Iranian- and Russian-backed Syrian government.

In response, Russian warplanes launch raids on Aleppo city "for the first time since 2016", the Observatory said.

The rebels seize control of most of Aleppo within a day, and hold more than 80 towns and villages in the north.

Russian Foreign Minister Sergei Lavrov speak with his Iranian and Turkish counterparts expressing concerns over the "dangerous" escalation of hostilities.

- December 1 -

The war monitor's head says "Aleppo city is out of control of Syrian regime forces" for the first time in more than a decade.

Iran's Foreign Minister Abbas Araghchi travel to Damascus to meet Assad, saying before his departure that Tehran would "firmly support the Syrian government and army".

The United States and its allies France, Germany and Britain call for "de-escalation", urging for the protection of civilians and infrastructure in Syria.

- December 2 -

Russian President Vladimir Putin and Iran's President Masoud Pezeshkian both pledged "unconditional support" for their ally, according to the Kremlin.

- December 5 -

The rebels captured Hama, Syria's fourth largest city, after days of fierce fighting with Assad's forces.

Syrian rebel chief Abu Mohammed al-Jolani says there would be "no revenge" after Hama's seizure.

China's embassy sends an urgent notice advising its citizens to leave Syria.

- December 6 -

The rebels are within striking distance of Syria's Homs, known as the "capital of the revolution".

HTS leader Jolani says the goal of the offensive was to overthrow Assad's rule, reiterating "our right to use all available means to achieve that goal".

Syrian troops and Iran-backed paramilitaries pull out of eastern Deir Ezzor city -- home to Iranian advisers brought in post-2011 -- and its surroundings.

More than 820 people, including 111 civilians, have been killed since the offensive began, the Observatory says.

The violence has displaced 280,000 people, with the UN warning that numbers could swell to 1.5 million.

- December 7 -

The rebels take Homs, and HTS leader says: "Damascus awaits you".

Defence ministry denies news of the army's withdrawal from around Damascus.

Turkish President Recep Tayyip Erdogan, whose government backs some armed groups in northern Syria, says Syria "is tired of war, blood and tears".

Lebanon's Hezbollah sends 2,000 fighters into Syria "to defend its positions", says a source.

- December 8 -

The army and other security forces pulls out of Damascus international airport after Assad reportedly flees the country, says the Observatory.

Rebels enter Damascus and declare the end of Assad rule, sending residents streaming into the streets celebrating.

Syrian Prime Minister Mohammed al-Jalali says he is ready to "cooperate" with any leadership chosen by the people and for any handover process.