10 Key Developments in the Syria Conflict
From the bloody repression of pro-democracy demonstrations to the rise of jihadists and intervention by regional and world powers, here are 10 key developments in Syria's devastating civil war.
More than 320,000 people have died in the six-year conflict, according to the Syrian Observatory for Human Rights. Millions more have fled their homes, with many seeking refuge abroad.
- Revolt and repression -
March 15, 2011: Unprecedented protests break out, demanding civil liberties and freedom for political prisoners after 40 years of repressive rule by the Assad family.
Denouncing "an armed rebellion by Salafist groups," the government crushes demonstrations in Damascus and the southern city of Daraa.
The protests continue to spread and demonstrators call for President Bashar al-Assad to step down.
In July, defected army colonel Riyadh al-Assad sets up the Turkey-based rebel Free Syrian Army (FSA). Islamist groups join the revolt.
- 'Barrel bombs' used -
March 1, 2012: Regime forces seize the rebel-held Baba Amr district of Syria's third city Homs after almost a month of heavy shelling.
July 17, 2012: FSA fighters launch a battle for Damascus, but the government holds firm.
From 2013, the regime pounds rebel strongholds across the country with improvised "barrel bombs."
- Hezbollah and Iran -
April 2013: Lebanon's Iran-backed Hizbullah says it is fighting alongside government forces.
Iran boosts its military support for longtime ally Assad.
- Chemical weapons -
August 21, 2013: Rebel backer Washington accuses the regime of killing more than 1,400 people with chemical weapons in rebel-held districts near Damascus.
In September, the United States and Assad ally Russia agree a plan to eliminate Syria's chemical weapons, averting punitive U.S. strikes against the regime.
- Rise of jihadists -
From 2013, jihadists, including the al-Qaida-linked al-Nusra Front, expand in the north at the expense of moderate rebels.
In 2014, the Islamic State group (IS) seizes swathes of territory before proclaiming a self-styled "caliphate" in areas it controls in both Syria and Iraq.
- Coalition air strikes -
In September 2014, U.S. president Barack Obama vows to build an international coalition to defeat IS.
Later that month, the U.S. and its allies launch air strikes against IS in Syria.
The strikes benefit Kurdish groups, which in 2013 declared autonomous administrations in Kurdish-majority areas.
In January 2015, coalition-backed Kurdish fighters oust IS from the flashpoint border town of Kobane.
- Russia intervenes -
September 30, 2015: Russia launches air strikes in support of Assad. Moscow says it is targeting "terrorist groups" including IS, but the opposition and the West accuse it of targeting non-jihadist rebels.
Government forces, on the back foot since March 2015, begin to retake territory.
- Turkey intervenes -
August 24, 2016: Turkey launches cross-border "Operation Euphrates Shield" to tackle both IS and Washington-backed Kurdish militia groups that Ankara considers "terrorists."
- Regime retakes Aleppo -
December 22, 2016: After a suffocating siege and a crushing offensive, the army declares it is in full control of second city Aleppo, which has been divided between rebels and government forces since 2012.
Thousands of rebels and civilians are evacuated under a deal sponsored by Iran, Russia and Turkey.
On December 30, a nationwide ceasefire comes into force under a Russia-Turkey accord which sidelines the U.S.
- 'Chemical' attack, U.S. missiles -
April 4, 2017: A suspected chemical attack kills 87 civilians, including 31 children, in rebel-held Idlib province. Western governments accuse Assad of using banned chemical weapons, which both Damascus and Moscow deny.
Overnight April 6-7, a barrage of 59 U.S. Tomahawk cruise missiles fired from warships in the eastern Mediterranean hits an airbase in central Syria, the first U.S. military action against the regime.