...Liwa al-Islam (Brigade of Islam) was established by Zahran Alloush, the son of Saudi-based religious scholar Abdullah Mohammed Alloush, after Syrian authorities released him from prison in mid-2011 where he had been serving time for his Salafist activism. The group claimed responsibility for carrying out the July 2012 Damascus bombing that killed Defense Minister Dawoud Rajiha, Deputy Defense Minister Asef Shawkat, and Assistant Vice President Hassan Turkmani. It was a driving force behind actions in the Damascus region. It cooperated and conducted joint operations with al-Nusra. In Sptember 2013 Saudi Arabia engineered Liwa al-Islam's merger with fifty other more or less Salafist groups as a counterweight to al-Nusra, which the Learned Elders of Islam considered was growing too powereful...published a statement claiming that their forces struck a Syrian Army chopper over the East Ghouta region of Damascus.
According to the statement, Jaish al-Islam fighters fired an anti-aircraft missile from their OSA system, scoring a direct hit on the Syrian Army chopper.
However,
there's no worse danger than telling a mother her baby is ugly...
the Jaish al-Islam statement did not clarify whether or not the Syrian Army chopper went down ‐ the Syrian military has not confirmed corroborated these claims.
The OSA surface-to-air system was captured by Jaish al-Islam in 2013, when their forces managed to capture a Syrian Air Defense base in the East Ghouta.