"At least three Shia divisions involved in successful battles against ISIS in Iraq-the Badr Brigade, Kata'ib Hezbollah, and the League of the Righteous-have acknowledged taking casualties in fighting in south and southeast Aleppo province," the statement said.
The US military confirmed that "they believe… at least one" unit of the Badr Brigade is fighting in southern Aleppo alongside other Iraqi militia groups" supported by "Russian airpower and Iranian troops-and all of whom are bolstering President Bashar al-Assad's Syrian Arab Army."
Researcher Philip Smith of the University of Maryland also told journalists that Iran and Russian air forces support rebels especially in Aleppo. In particular, it is known that the brigade "Asaib Ahl al-Haq"(the "League of the Virtuous") is backed by the Iranian military.the international coalition led by the United States during the Iraq war.
According to the UN, the ongoing armed conflict in Syria claimed the lives of 220,000 people since March 2011. Government troops are confronted with a gang of militants belonging to various armed groups. The most active terrorist groups are Daesh and al-Nusra front forces.
There is no united front to fight Daesh — Syrian and Iraqi governmental forces, the US-led coalition (so far limited to airstrikes) as well as the Kurds, Lebanese and Iraqi Shia rebels are all using different means and tactics. Adding to the Syrian Army's anti-terror effort is Russia's ongoing air campaign in Syria which was launched on September 30, when more than fifty Russian warplanes, including Su-24M, Su-25 and Su-34 jets, commenced precision airstrikes on Daesh and Al-Nusra Front targets in Syria at the behest of Syrian President Bashar Assad.