What just happened in Aleppo, and what it means for Syria's civil war

Opposition forces seeking to overthrow Syria's President Bashar al-Assad launched their biggest offensive in years last week, retaking the northern city of Aleppo and driving government forces out of the region.

It was the first significant development in years in Syria's grinding civil war, which after almost 14 years had largely fallen from the world's headlines. It also raises fresh questions about the opposing sides, who supports them, and what might happen next. Here's what we know:

Syrian rebels launched a two-pronged offensive on Aleppo last week, gaining control of the country's second largest city amid little resistance from government troops, according to residents and fighters. 

The insurgents are a coalition of Turkey-backed mainstream secular groups spearheaded by Hayat Tahrir al-Sham (HTS), an Islamist group designated as a terrorist organization by the U.S. and United Nations.

The rebels have since pressed their advance to the south and southwest of Aleppo, capturing territory in Hama province and moving into the countryside around Idlib. 

HTS, formerly known as the Nusra Front, was al-Qaeda's official wing in the Syrian war but the groups broke ties in 2016. 

Another rebel group — the National Coalition of Syrian Revolution and Opposition Forces, the internationally recognized Syrian opposition — launched a separate offensive from north of Idlib. It represents anti-Assad groups including the Turkey-backed Syrian National Army or Free Syrian Army.

The assault followed the recent ceasefire between Israel and Hezbollah, ending more than a year of fighting that started shortly after Israel went to war with Hamas in Gaza.

Hadi al-Bahra, president of the National Coalition, says rebels began preparing to seize Aleppo a year ago but were delayed by the Israel-Hamas war.

"The moment there was a ceasefire in Lebanon, they found that opportunity... to start," he said. 

Earlier this year, Israeli airstrikes in Aleppo hit both Hezbollah weapons depots and Syrian government forces, among other targets, according to an independent monitoring group. Israel rarely acknowledges strikes against Aleppo or other government-held areas of Syria.

Iran which, like Hezbollah, supports the regime, has also been weakened by recent Israeli airstrikes.

Russia — Assad's main international backer — is meanwhile preoccupied with its war in Ukraine. 

Aleppo, an ancient centre of commerce and culture in the Middle East, was home to 2.3 million people before the war. Rebels seized the east side of the embattled city in 2012, and it became the proudest symbol of the advance of armed opposition factions, but changed hands again when a brutal air campaign by Russia helped al-Assad retake the city.