VIENNA — Seeking to salvage and reinforce a shaky truce, world and regional powers agreed Tuesday to try to turn the faltering pause in Syria’s fighting into a comprehensive cease-fire and boost humanitarian aid deliveries with the hope of restarting peace talks.
But underscoring the difficulties in ending the five-year war that has left hundreds of thousands dead and fueled the rise of Islamic extremists, the more than 20 nations were not able to outline specific penalties for non-compliance with the truce and the U.N.
