Here is some background about the on-going civil war in Syria. Since the war began in 2011, more than 100,000 Syrians have been killed, according to the United Nations.
Facts: Bashar al-Assad has ruled Syria as president since July 2000. His father, Hafez al-Assad, ruled Syria from 1970-2000.
The ongoing violence against civilians has been condemned by the Arab League, the European Union, the United States, and other countries.
Timeline: March 2011 - Violence flares in Daraa after a group of teens and children are arrested for writing political graffiti. Dozens of people are killed when security forces crack down on demonstrations.
March 24, 2011 - In response to continuing protests, the Syrian government announces several plans to appease citizens. State employees will receive an immediate salary increase. The government also plans to study lifting Syria's long standing emergency law and the licensing of new political parties.
March 30, 2011 - President al-Assad addresses the nation in a 45-minute televised speech. He acknowledges that the government has not met the people's needs but he does not offer any concrete changes. The state of emergency remains in effect.
April 21, 2011 - Al-Assad lifts the country's 48-year-old state of emergency. He also abolishes the Higher State Security Court and issues a decree "regulating the right to peaceful protest, as one of the basic human rights guaranteed by the Syrian Constitution."
May 18, 2011 - The U.S. imposes sanctions against Syrian President Bashar al-Assad and six other senior Syrian officials. The Treasury Department details the sanctions by saying, "As a result of this action, any property in the United States or in the possession or control of U.S. persons in which the individuals listed in the Annex have an interest is blocked, and U.S. persons are generally prohibited from engaging in transactions with them."
August 18, 2011 - The U.S. imposes new economic sanctions on Syria, freezing Syrian government assets in the U.S., barring Americans from making new investments in the country and prohibiting any U.S. transactions relating to Syrian petroleum products, among other things.
September 2, 2011 - The European Union bans the import of Syrian oil.
September 23, 2011 - The European Union imposes additional sanctions against Syria, due to "the continuing brutal campaign" by the government against its own people.
October 2, 2011 - A new alignment of Syrian opposition groups establishes the Syrian National Council, a framework through which to end President al-Assad's government and establish a democratic system.
October 4, 2011 - Russia and China veto a U.N. Security Council resolution that would call for an immediate halt to the crackdown in Syria against opponents of President Bashar al-Assad. Nine of the 15-member council countries, including the United States, voted in favor of adopting the resolution.
November 12, 2011 - The Arab League suspends Syria's membership, effective November 16, 2011.
November 27, 2011 - Foreign ministers from 19 Arab League countries vote to impose economic sanctions against the Syrian regime for its part in a bloody crackdown on civilian demonstrators.
November 30, 2011 - Turkey announces a series of measures, including financial sanctions, against Syria.
December 19, 2011 - Syria signs an Arab League proposal aimed at ending violence between government forces and protesters.
January 28, 2012 - The Arab League suspends its mission in Syria as violence there continues.
February 2, 2012 - A U.N. Security Council meeting ends with no agreement on a draft resolution intended to pressure Syria to end its months-long crackdown on anti-government demonstrators.
February 4, 2012 - A U.N. Security Council resolution condemning action against Syria is not adopted after Russia and China vote against it.
February 6, 2012 - The U.S. closes its embassy in Damascus and recalls its diplomats.
February 7, 2012 - The Gulf Cooperation Council announces its member states are pulling their ambassadors from Damascus and expelling the Syrian ambassadors in their countries.
February 16, 2012 - The United Nations General Assembly passes a nonbinding resolution endorsing the Arab League plan for Syrian president Bashar al-Assad to step down. The vote was 137 in favor and 12 against, with 17 abstentions.
February 26, 2012 - Syrians vote on the constitutional referendum in polling centers across the country. Almost 90% of voters approve the changes to the constitution.
March 13, 2012 - Kofi Annan, the U.N. special envoy to Syria, meets in Turkey with government officials and Syrian opposition members. He visits Syria over the weekend where he calls for a cease-fire, the release of detainees and allowing unfettered access to relief agencies to deliver much needed aid.