The assassination of a senior Syrian rebel commander who led one of the most powerful groups fighting President Bashar Assad's forces dealt a significant setback to the opposition.
It could also reshuffle the line-up of key players on the ground ahead of the planned peace talks in Geneva next month.
The Army of Islam and allied militant groups in Syria mourned the killing of Zahran Allouch, while government supporters and the Islamic State (IS) group cheered his death - a reflection of his role in fighting both sides in the Syrian civil war.
He was killed in air strikes that targeted the group's headquarters during a meeting on Friday, and instantly killed along with a number of senior commanders of his Army of Islam group and those of the ultraconservative Ahrar al-Sham and the Faylaq al-Rahman groups.
The Syrian army claimed responsibility for the air strikes, although many among the opposition blamed Russia, which has been bombing IS targets and other insurgent groups since late September.
Allouch was a controversial figure in the war and an authoritative rebel leader who commanded thousands of fighters on the doorstep of Damascus, the seat of Assad's power.
His death may have contributed - at least partially - to a delay in an agreed-on pull-out of thousands of militants and their families from neighbourhoods on the southern edge of Damascus.
The withdrawal, supposed to start on Saturday, was to involve mainly militants from IS who earlier this year overran the Yarmouk area, which is home to a Palestinian refugee camp and has been hotly contested in the war, and two adjacent neighbourhoods.
A Palestinian official in Damascus, Anwar Abdulhadi, said the withdrawal is being delayed for "logistical reasons".
But Lebanon's Hezbollah-run TV station Al Manar said Allouch was a key figure in arranging the rare deal, and that his assassination has delayed its implementation.