UN Special Envoy for Syria Staffan de Mistura attends the plenary session of Syria peace talks brokered by Iran, Russia and Turkey in Astana on November. AFP
UN Special Envoy for Syria Staffan de Mistura attends the plenary session of Syria peace talks brokered by Iran, Russia and Turkey in Astana on November. AFP

Staffan de Mistura laments 'missed opportunities' at lacklustre final Syria summit