Syrian rebel fighters

In this Tuesday, Sept. 17, 2013 photo, a Syrian opposition fighter rests inside a cave at a rebel camp in the Idlib Provence countryside of Syria. The main Syrian opposition coalition urged the international community to take swift action against the regime of President Bashar Assad in response to a U.N. finding that the nerve agent sarin was used in a deadly attack near the capital last month.

Narciso Contreras/AP

A Syrian opposition fighter rests inside a cave at a rebel camp in the Idlib province countryside of Syria. The main Syrian opposition coalition urged the international community to take swift action against the regime of President Bashar Assad in response to a UN finding that the nerve agent sarin was used in a deadly attack near the capital last month 

Syrian rebel fighters stand in a damaged section of the Umayyad Mosque complex in the old part of Syria's northern city of Aleppo on April 16, 2013. After nine months of fighting that has devastated many districts in Aleppo, rebels now control more than half of the city.

Dimitar Dilkoff/AFP

Syrian rebel fighters stand in a damaged section of the Umayyad Mosque complex in the old part of Syria‘s northern city of Aleppo on April 16 2013. After nine months of fighting that has devastated many districts in Aleppo, rebels now control more than half of the city.