The Syrian government will need to decide whether to return to peace talks adjourned by the United Nations envoy on Wednesday, its chief delegate said, accusing the opposition of pulling out because it was losing the fight on the ground. "The military developments on the ground were crucial. Notice that the (opposition) decision of withdrawal came after opening the road to Nubul and Zahraa," Syria's U.N. ambassador Bashar al-Ja'afari said, referring to the Syrian army and its allies having broken a three-year rebel siege of two Shi'ite towns in northern Aleppo province.