FILE - In this undated file photo from World War I, German Red Cross members carry bottles of liquid to revive those who have succumbed to gas bombs during battle. A century after German troops opened the taps on a line of chlorine tanks to send a poisonous cloud drifting across no man's land and into World War I Allied trenches, chemical warfare has come full circle. A report last year set up by the Organization for the Prohibition of Chemical Weapons said a toxic chemical, almost certainly chlorine, was used repeatedly in attacks on villages in Northern Syria. (AP Photo, File)
German Red Cross members treat victims of a gas attack during the First World War. AP Photo

Assad and the reawakening of a Great War curse