Rebels in Syria's Eastern Ghouta surrendered their heavy weapons and their leader left the enclave, a monitor said Thursday, signalling the end of one of the bloodiest assaults of Syria's seven-year war.
The Syrian flag was raised above the central mosque in Douma, the town where the regime is accused of carrying out a chemical attack that sparked outrage and threats of Western military action.
US President Donald Trump was mulling his options and British Prime Minister Theresa May called an emergency cabinet meeting Thursday, as the Syrian army braced for Western strikes, hiding assets and clearing key buildings.
Jaish al-Islam, which has controlled Eastern Ghouta's main town for years, had balked at a Russian-brokered deal like those that saw other factions bussed to northern Syria.
The group's political chief told AFP it was a chemical attack by the regime that forced them to accept Russia's terms and evacuate their former bastion.
"Of course, the chemical attack is what pushed us to agree" to a withdrawal from Douma, said Yasser Dalwan.
Western powers such as France and the United Nations have alleged the regime used chemical weapons on Douma last Saturday.
Damascus has said the case was entirely fabricated to justify military action against the regime and that international chemical experts would arrive in the country Thursday.
The OPCW global watchdog said the team was "on its way to Syria and will start its work as of Saturday" on a fact-finding mission into the alleged attack.
Regime forces had yet to take over Douma Thursday but, according to the Syrian Observatory for Human Rights, the rebels gave up their heavy weapons.
"Jaish al-Islam fighters handed over their heavy weapons to Russian military police in the town of Douma on Wednesday," the Britain-based monitoring group said.
Their top leader Issam Buwaydani boarded a convoy out of Ghouta with thousands of other fighters and their relatives, it said.
Douma residents told AFP that Syria's national red, white and black flag with two green stars was raised on Wednesday above the main mosque, which was also used as the office of the town's opposition-run council.
But a dispute subsequently erupted, shots were fired and the flag was taken down, the residents said.
Russian military police, who had started deploying in the town as part of a deal that would allow some rebels to disarm and stay in Douma, also left after the incident, the residents said.
Simultaneously carrying out air strikes, brokering talks and supervising humanitarian operations, Russia was the key player in an assault that left at least 1,700 civilians dead.
"Today a significant event in the history of Syria took place," Major General Yury Yevtushenko, head of the Russian military's centre for reconciliation in Syria, was quoted as saying by the Interfax news agency.
"The raising of a regime flag over a building in the town of Douma signified control over this town and consequently over Eastern Ghouta as a whole," he said.
It was not clear whether he was referring to the flag that was taken down or to another.
Moscow also said Russian military police had returned to the town on Thursday and were in full control.
"From today, units of the Russian armed forces' military police are working in the town of Douma," the defence ministry said.
Yet chaos and confusion prevailed in the streets of Douma, where civilians appeared to have very little information on the latest political developments.
Many residents were preparing to take what should be some of the last buses leaving the region to head to parts of northern Syria still under rebel control.
A military official said around 30 of 80 buses brought to Douma for the evacuations had already left.
According to the Russian military, more than 160,000 people have been evacuated from Eastern Ghouta, which only two months ago was a sprawling rebel enclave within mortar range of central Damascus.
The government of President Bashar al-Assad, which since Russia's military intervention in 2015 has gradually reasserted what was once a very tenuous grip on the country, was keen to secure an area that directly threatened the capital.
"Victory in Ghouta is a critical point," Bouthaina Shaaban, a top Assad adviser, said on the Lebanese channel Al-Mayadeen.
"It has sent a message to the whole world that Syria's army and its allies can liberate every inch of Syrian territory," she said.
The Syrian pound has risen significantly as the operation to flush rebels out of Ghouta wrapped up.
Regime and allied forces are next expected to train their sights on areas in southern Damascus that are almost empty of civilians but still controlled by the Islamic State jihadist group (IS).
According to the Observatory, more than 350,000 people have been killed in seven years of conflict, including a proportion of children that has risen sharply over the past year.
While the scramble for Syria that followed the collapse of IS's self-styled "caliphate" last year is winding down in some parts of Syria, the humanitarian emergency is still acute.
According to the International Committee of the Red Cross, 2.9 million people were forced from their homes last year, or nearly 8,000 people every day.