A Syrian military offensive backed by heavy Russian air strikes threatened to cut critical rebel supply lines into the northern city of Aleppo, as peace talks in Switzerland appeared to be in jeopardy on Wednesday.
The government attack north of Aleppo that began in recent days is its first major offensive there since Russian air strikes began on September 30.
Rebels described the assault as the most intense yet, with activists reporting that 45 civilians have been killed. One commander said that opposition-held areas of Syria's largest city were at risk of being encircled entirely by the government and allied militia, appealing to foreign states that back the rebels to send more weapons.