Syrian Foreign Minister Walid al-Moallem said on Sunday, May 26, 2013, during a visit to Baghdad that his government has agreed in principle to take part in an international conference in Geneva next month aimed at ending Syria's civil war. (AP Photo/Hadi Mizban, Pool)
Rebel fighters celebrate after purportedly capturing an army base in Nairab, northwestern Syria, Thursday, May 23, 2013. The video is consistent with independent AP reporting. (AP Photo/Ugarit News via AP video)
Qatari foreign minister Sheik Hamad bin Jassim al-Thani talks during an Arab League committee emergency meeting on Syria at the league’s headquarters in Cairo, Egypt, Thursday, May 23, 2013, ahead of an international peace conference to end the country’s civil war. (AP Photo/Amr Nabil)
** FILE ** This Wednesday, Aug. 19, 2009, file photo shows Syrian President Bashar Assad, seen, during a meeting with his Iranian counterpart Mahmoud Ahmadinejad, unseen, at the presidency in Tehran, Iran. (AP Photo/Vahid Salemi, File)
**FILE** This citizen journalism image from May 14, 2013, provided by Aleppo Media Center and authenticated based on its contents and other AP reporting, shows the mother of a Syrian rebel cleaning a rifle in Aleppo, Syria. (Associated Press/Aleppo Media Center AMC)
This image taken from video obtained from Ugarit News, which has been authenticated based on its contents and other AP reporting, shows Syrian rebels preparing to fire a rocket at Mannagh air base in Aleppo province, Syria, Monday, May 13, 2013. (AP Photo/Ugarit News via AP video)