Islamic State fighters were reported to have tightened their grip on a Syrian government supply route to Aleppo on Tuesday as the army battled to retake the road as part of its campaign to seize the city.
As Damascus accepted a U.S.-Russian plan for a "cessation of hostilities" between the government and rebels due to take effect on Saturday, heavy Russian airstrikes were also said to be targeting one of the last roads into opposition-held parts of Aleppo.
The plan announced by the United States and Russia on Monday is the result of intensive diplomacy to end the five-year-long war. But rebels say the exclusion of Islamic State and the al-Qaida-linked Nusra Front will give the government a pretext to keep attacking them because its fighters are widely spread in opposition-held areas.