Both are typical visual signatures of white phosphorus, which can be loaded into artillery shells. The Islamic State has made claims of use of white phosphorous by United States-led forces before as part of its efforts to discredit its enemies. White phosphorus, along with other incendiaries, has been used by Syrian government forces battling insurgents in Aleppo and elsewhere. Abdullah, a Raqqa resident living in Beirut, said his relatives had seen what they believed was white phosphorus being used in the city. The Islamic State has become increasingly restrictive about sharing information with the outside world, so residents spoke on the condition of anonymity for fear of reprisals.

Source: New York Times June 10, 2017 19:18 UTC