Demonstrators wave Syrian opposition flags during a protest in Istanbul against the government of Syria's President Bashar Assad, on March 15. Osman Orsal/Reuters /Landov hide caption

itoggle caption Osman Orsal/Reuters /Landov

Syrians carry a large revolution flag and chant slogans during a protest in Aleppo, Syria, where young people and children sang songs against President Bashar Assad and the Syrian regime, Dec. 21, 2012. Virginie Nguyen Hoang/AP hide caption

itoggle caption Virginie Nguyen Hoang/AP

An image taken from video obtained from the Shaam News Network, authenticated by AP reporting, shows attempts to rescue the wounded in Idlib, northern Syria following heavy bombing from military warplanes. Uncredited/ASSOCIATED PRESS hide caption

itoggle caption Uncredited/ASSOCIATED PRESS