The Syrian army was on Monday reported to be sending reinforcements to Aleppo, where renewed fighting is threatening a fragile truce in the run-up to the next round of peace talks.
Underlining the conflict's regional dimensions, Iranian media announced the first deaths of members of its regular army in Syria, a week after Tehran said army commandos had been deployed in support of Damascus. Iran's military support has so far mostly been provided by the elite Revolutionary Guard Corps.
An eruption of fighting near the ancient city of Aleppo in the last two weeks marks the most serious challenge yet to a "cessation of hostilities" brokered by the United States and Russia with the aim of facilitating peace talks.