ISIS has reportedly used mustard gas in an attack on a military airport in Syria 's eastern province of Dar Zor . The neighbourhoods surrounding the airport are under ISIS ’ control , and the facility has been attacked repeatedly by the group . The Syrian army backed by heavy Russian air strikes was able last January to drive back the hardline militants from several villages near the airport but has so far failed to dislodge them. Deir Ali borders Iraq , and control of the airport gives ISIS a link between its de facto capital , Raqqa and its forces across the border . The army , with support from Turkey , attempted to push back militants from the areas surrounding the airport , but failed to remove them all . It is unclear how many casualties were sustained in the attack .
ISIS has reportedly used mustard gas in an attack on a military airport in Syria 's eastern province of Dar Zor . The neighbourhoods surrounding the airport are under ISIS ’ control , and the facility has been attacked repeatedly by the group . Deir Ali borders Iraq , and control of the airport gives ISIS a link between its de facto capital , Raqqa and its forces across the border . The army , with support from Turkey , attempted to push back militants from the areas surrounding the airport , but failed to remove them all . It is unclear how many casualties were sustained in the attack .