March 15, 2012 - The Gulf Cooperation Council announces that the six member countries will close their Syrian embassies and calls on the international community "to stop what is going on in Syria." The council members include the United Arab Emirates, Bahrain, Saudi Arabia, Oman, Qatar and Kuwait.
March 21, 2012 - After a year of fighting, the U.N. believes more than 8,000 people have died. Opposition activists claim the number to be higher than 10,000 and most of the dead are civilians.
March 27, 2012 - The Syrian government accepts U.N. envoy Kofi Annan's plan to end violence. The proposal seeks to stop the violence, give access to humanitarian agencies, release detainees, and start a political dialogue to address the concerns of the Syrian people.
April 1, 2012 - At a conference in Istanbul, Turkey, the international group Friends of the Syrian People formally recognizes the Syrian National Council as a legitimate representative of the Syrian people.
June 10, 2012 - Abdul Basit Sieda, a Syrian native now living in Sweden, is now Syria's National Council leader.
June 13, 2012 - The U.N. Security Council has authorized up to 300 unarmed military observers for a 90-day mission in Syria. The monitors are tasked with observing a cease-fire that was supposed to go into effect April 12, though both the Syrian regime and opposition have reported at least hundreds of killings since then. In addition, observers are tasked with supporting the implementation of Annan's peace plan, which also calls for access for humanitarian groups, the release of arbitrarily arrested detainees and the start of a political dialogue.
June 16, 2012 - The U.N. suspends its monitoring mission due to intensifying violence.
July 23, 2012 - The Syrian Foreign Ministry spokesman, Jihad Makdissi, threatens to use chemical and biological weapons against outside forces, "No chemical or biological weapons will ever be used, ... unless Syria is exposed to external aggression."
July 30, 2012 - The Syrian Charge d'Affaires in London, Khaled al-Ayoubi, resigns stating he is "no longer willing to represent a regime that has committed such violent and oppressive acts against its own people."
August 2, 2012 - U.N. Secretary General Ban Ki-moon announces that Special Envoy for Syria Kofi Annan will not renew his mandate when it expires at the end of August.
August 6, 2012 - Syrian Prime Minister Riyad al-Hijab's resignation from office and defection from Assad's regime is read on Al Jazeera by his spokesman Muhammad el-Etri. Hijab and his family are said to have left Syria overnight arriving in Jordan. Hijab is the highest-profile official to defect.
August 9, 2012 - Syrian television reports that President al-Assad has appointed Health Minister Wael al-Halki as the new prime minister.
October 3, 2012 - Five people are killed by Syrian shelling in the Turkish border town of Akcakale. In response, Turkey fires on Syrian targets and its parliament authorizes a resolution giving the government permission to deploy its soldiers to foreign countries.
November 11, 2012 - Israel fires warning shots toward Syria after a mortar shell hits an Israeli military post. It is the first time Israel has fired on Syria across the Golan Heights since the 1973 Yom Kippur War.
November 11, 2012 - Syrian opposition factions formally agree to unite as the National Coalition for Syrian Revolutionary and Opposition Forces.
November 13, 2012 - Sheikh Ahmed Moaz al-Khatib is elected leader of the Syrian opposition collective, the National Coalition for Syrian Revolutionary and Opposition Forces.
January 6, 2013 - Assad announces he will not step down and that his vision of Syria's future includes a new constitution and an end to support for the opposition, which he calls terrorists. The opposition refuses to work with Assad's government.
February 12, 2013 - The U.N. Security Council estimates that the number of civilians killed in the two-year civil war in Syria is approaching 70,000.
March 19, 2013 - The National Coalition for Syrian Revolutionary and Opposition Forces elects American-educated Ghassan Hitto as its prime minister. Though born in Damascus, Hitto has spent much of his life in the United States, and holds dual U.S. and Syrian citizenship.
April 25, 2013 - Secretary of Defense Chuck Hagel announces the United States has evidence that the chemical weapon sarin has been used in Syria on a small scale.
May 6 - A U.S. official tells CNN that Israeli forces conducted an airstrike in Syria on May 5, as well as one the previous week. Sunday's strike targeted a research facility in a mountainous area near Damascus and weapons that were to be transferred to Hezbollah, and the earlier strike targeted Fateh 110 missiles stored at the Damascus airport.
May 17, 2013 - The U.N.'s refugee agency reports that over 1.5 million Syrians have left their country to escape the war.
May 27, 2013 - European Union nations end the arms embargo against the Syrian rebels.
May 27, 2013 - U.S. Senator John McCain visits rebels in Syria. It is reported that he is the highest ranking U.S. official to visit since the beginning of the war.
June 13, 2013 - The Obama Administration says that Syria has crossed a 'red line' with its use of chemical weapons, including the nerve agent sarin gas, against rebels and indicates that it will be stepping up its support of the rebels, who have been calling for the United States and others to provide arms need to battle al-Assad's forces.