It is not illegal under international law for militaries to possess and use white phosphorus, and the United States’ and other Western militaries say they use it mainly to create smoke screens to hide troop movements. But it can also be used as an incendiary weapon, setting very hot fires. And like thermite and napalm, it is proscribed in civilian areas by international law.
A United States official acknowledged that American forces who are fighting the Islamic State, also known as ISIS, in Iraq and Syria have access to white phosphorus munitions, but he said it was not being used against personnel. The official spoke on the condition of anonymity because he was not authorized to discuss the use of the munition.
The spokesman for the American-led task force that is fighting the militants, Col. Ryan Dillon, said that as a matter of policy he could not discuss the use of specific munitions. But he added that “in accordance with the law of armed conflict, white phosphorus rounds are used for screening, obscuring and marking in a way that fully considers the possible incidental effects on civilians and civilian structures.”
