see more

(C, L to C, R) Russian Foreign Minister Sergei Lavrov, US Secretary of State John Kerry and UN Special envoy for Syria Staffan de Mistura lead talks on Syria on May 17, 2016 in Vienna. Senior envoys from world and regional powers meet once again in Vienna in an effort to salvage stumbling efforts to halt Syria's bloody civil war. / AFP / POOL / LEONHARD FOEGER (Photo credit should read LEONHARD FOEGER/AFP/Getty Images)

(C, L to C, R) Russian Foreign Minister Sergei Lavrov, US Secretary of State John Kerry and UN Special envoy for Syria Staffan de Mistura lead talks on Syria on May 17, 2016 in Vienna. 
Senior envoys from world and regional powers meet once again in Vienna in an effort to salvage stumbling efforts to halt Syria's bloody civil war. / AFP / POOL / LEONHARD FOEGER        (Photo credit should read LEONHARD FOEGER/AFP/Getty Images)