In this citizen journalism image provided by Edlib News Network, ENN, which has been authenticated based on its contents and other AP reporting, smoke rises after explosives were dropped by a Syrian government warplane, in Idlib province, northern Syria, Friday, Aug. 30, 2013. United Nations experts are investigating the alleged use of chemical weapons in Syria as the United States and its allies prepare for the possibility of a punitive strike against President Bashar Assad’s regime, blamed by the Syrian opposition for the attack. The international aid group Doctors Without Borders says at least 355 people were killed in the Aug. 21 attack in a suburb of Damascus, the Syrian capital.(AP Photo/Edlib News Network ENN)