A boy, affected by what activists say is nerve gas, breathes through an oxygen mask in the Damascus suburb of Saqba

A boy, affected by what activists say is nerve gas, breathes through an oxygen mask in the Damascus suburb of Saqba, August 21, 2013 in this handout provided by Shaam News Network. REUTERS/Maher al-Zaybaq/Shaam News Network/Handout via Reuters