Why is this happening now?published at 13:23 Greenwich Mean Time
BBC Monitoring

A coalition of rebel groups led by the Hayat Tahrir al-Sham (HTS), an Islamist militant group, now controls Syria’s second largest city Aleppo. It is threatening to grab further territory and push towards Damascus – but why is this happening now?
The rebels launched their offensive in northern Syria on 27 November, the same day a ceasefire took effect in the war between Israel and Hezbollah in neighbouring Lebanon.
Syrian President Bashar al-Assad’s forces, supported by Russian air strikes, have so far not offered effective resistance, raising questions about the Damascus government’s capacity to act.
Both Iran-backed Hezbollah and Russia, crucial backers of Assad’s government, have recently been mired in their own conflicts. Hezbollah’s current weakened state after Israel’s ground offensive and air strikes this year may have emboldened HTS.
After years of being locked behind frozen frontlines, Syria’s militants, now better equipped and organised, moved rapidly to capture strategic towns and cities from the government. Seizing control of Hama on Thursday, they are now at the gates of Homs in western Syria, which borders Lebanon.
Abu Mohammed al-Jolani, the leader of the HTS rebel alliance, says the goal of the offensive is to overthrow Assad’s rule.
Syria’s civil war began in 2011 after Assad’s brutal crackdown on democracy protests.
Separately, Turkish-backed groups have launched operations against largely Kurdish-held areas in northern Syria, which is in line with Ankara’s long-communicated desire to move against Kurdish forces there and to control a swathe of land south of its border as a security buffer zone.