Here are the main events in the uprising in Syria since it began:
March 15, 2011 - About 40 people join a protest in Old Damascus, chanting political slogans in a brief first challenge to the ruling Baath Party before dispersing into side streets.
March 18 - Security forces kill three protesters in southern Deraa, residents say. The demonstrators were demanding political freedoms and an end to corruption.
March 22 - Hundreds of people march in Deraa and Nawa demanding freedom in the fifth straight day of demonstrations.
March 24 - President Bashar al-Assad orders the formation of a committee to study scrapping the emergency law in place in Syria for the last 48 years. The emergency law is lifted on April 19.
March 25 - At least 200 people march in Damascus and there are reports of at least 23 dead around the country including, for the first time, in Damascus.
July 31 - Syrian tanks storm Hama, residents say, after a month-long siege. At least 80 people are killed.
September 15 - Syrian opposition activists announce a Syrian National Council to provide an alternative to government.
November 12 - The Arab League suspends Syria.
December 7 - Assad denies ordering troops to kill peaceful demonstrators, telling U.S. television channel ABC only a "crazy" leader kills his own people.
December 19 - Syria signs Arab League peace plan and agrees to let observers into the country to monitor the deal.
December 23 - Twin suicide bombs target two security buildings in Damascus, killing 44 people. Syria blames al Qaeda while the opposition blames the government.
February 4, 2012 - Russia and China veto a resolution in U.N. Security Council, backed by Arab League, calling for Assad to step down. The General Assembly approves a resolution on February 16 endorsing the Arab League plan calling for Assad to step aside.
February 22 - More than 80 people are killed in Homs including two foreign journalists. Hundreds of people have now been killed in daily bombardments of the city by Assad's besieging forces.
February 23 - Former U.N. Secretary-General Kofi Annan is appointed U.N.-Arab League envoy to Syria.
February 24 - Foreign ministers from more than 50 countries meet in Tunis for the inaugural "Friends of Syria" meeting. Russia and China, allies of Syria, do not attend.
February 28 - Assad decrees that a new constitution is in force after officials say nearly 90 percent of voters endorsed it in a February 26 referendum. Opponents and the West dismiss it as a sham.
March 1 - Syrian rebels pull out of the besieged Baba Amr district of Homs after more than three weeks of bombardment.
March 11 - Annan ends talks with Assad and leaves Syria with little sign of progress.
March 27 - Syria accepts the U.N.-sponsored peace plan.
April 12 - U.N.-backed ceasefire comes into effect. Four days later monitors start to monitor the ceasefire in Syria.
May 7 - Syria says voters turned out in large numbers for a parliamentary election. The Opposition denounces it as a sham.
May 10 - Annan condemns attacks in Damascus in which two bomb explosions kill 55 people and wound 372. A week later U.N. Secretary-General Ban Ki-moon says he believes al Qaeda was responsible. He also says 10,000 people have now been killed.
May 25 - At least 108 people are killed, including many children, in attacks in the region of Houla. Two days later the Security Council unanimously condemns the killings.
June 1 - Annan says he is "frustrated and impatient" over the continuing killings and wants faster progress.
June 3 - In a rare address to parliament, Assad condemns the "abominable" massacre in Houla, saying even monsters would not carry out such acts.
June 5 - Syria bans 17 Western diplomats in retaliation for the expulsion of Syrian envoys from their capitals. On the same day Syria agrees to allow the United Nations and international agencies to expand humanitarian operations in Syria.
June 5/6 - Troops and militiamen loyal to Assad are accused of killing at least 78 people at Mazraat al-Qubeir, near Hama.
June 6 - Assad names party stalwart Riyad Hijab to form a new government, signaling no political concessions to the 15-month-old uprising.
June 12 - The uprising has grown into a full-scale civil war U.N. peacekeeping chief Herve Ladsous says.
June 16 - Escalating violence in Syria forces U.N. observers to suspend operations.
June 22 - Syrian troops shoot down a Turkish warplane in an incident Damascus says is self-defense but which Ankara brands an "act of aggression".
June 26 - Assad says his country is "at war".
June 27 - Gunmen storm Ikhbariya television's offices, headquarters, bombing buildings and shooting dead three journalists and four guards, state media says.
For an Interactive look at Syria click on link.reuters.com/pyt37s
(Reporting by David Cutler, London Editorial Reference Unit; Editing by Andrew Heavens)