Turkey’s supply line to opposition groups operating in and around Aleppo has been cut off due to Russian airstrikes and pro-government forces weakening rebel groups. Russian airstrikes across northern Syria has driven the epicenter of war towards the north of Aleppo following Turkey’s shooting down of its warplane last year. At the same time pro-government forces have broken a rebel siege of two villages in the north, cutting Turkey’s supply line to opposition groups. Yahoo News reports: Government troops, accompanied by Iran-backed Shiite militias and Hezbollah forces, apparently reached the cities of Nubl and Zahraa with the help of heavy Russian airstrikes on Wednesday. The opposition had held these cities since 2012, according to the Institute for the Study of War. A stepped-up Russian bombing campaign in the Bayirbucak region of northwest Syria, near the strategically important city of Azaz, had primarily targeted the Turkey-backed Turkmen rebels and civilians — and the Turkish aid convoys that supplied them. As a result, Turkey’s policy in Syria of bolstering rebels fighting Syrian President Bashar Assad’s regime — and establishing a “safe zone” for displaced Syrians that might hinder the regime’s efforts to take Aleppo — has been unraveling for months, and now appears to have [...]