Initial field tests have indicated that Islamic militants may have used mustard gas in an Aug. 11 attack on Kurdish peshmerga forces in northern Iraq, a senior U.S. commander said Friday.
Fragments of mortar shells fired at the Kurds turned up positive for the chemical HD (sulfur mustard) "but that is a presumptive field test and it is not conclusive,” said Marine Brig. Gen. Kevin Killea, chief of staff for Combined Joint Task Force -- Operation Inherent Resolve.
"We have only a field test that shows us the presence of HD on those fragments. Until we do other tests, we won't be able to have a firm decision on exactly what happened there,” Killea said. The additional testing was expected to take several weeks.
The introduction of chemical warfare by ISIS would represent a major escalation but "From a coalition perspective, we really don't need another reason to hunt down ISIL (ISIS) and kill them wherever we can and whenever we can," Killea said.
In a video briefing to the Pentagon, Killea said that the U.S. was also seeking to confirm the alleged use of chemical weapons in two attacks in Syria in June.
The Aug. 11 attack in Iraq was near the town of Mahmour, about 37 miles southwest of the Kurdish regional capital of Irbil.
In a statement last week, the German Defense Ministry said that about 60 Kurdish fighters suffered from breathing difficulties as a result of the attack. German troops serving as advisers to the Kurds in the area were not injured, the statement said.
German Defense Ministry spokesman Boris Nannt later said he could not confirm "in what manner and form" the Kurdish fighters had experienced breathing difficulties.
The Kurds later brought the shell fragments to U.S. officials at a camp near one of the operations centers in the Kurdish region, Killea said.
Mustard gas is a deadly blistering agent that was used extensively in World War I and can be dispersed by artillery shells and rockets.
Several reports from the region have speculated that ISIS may have obtained mustard gas in Syria. The regime of Syrian President Bashar al-Assad admitted to having stores of mustard gas in 2013, when it agreed to give up its chemical weapons arsenal.
Last week, Alistair Baskey, a spokesman for the White House's National Security Council, said in a statement that the U.S. was taking the allegations of chemical warfare by ISIS "very seriously" while seeking more information.
"We continue to monitor these reports closely, and would further stress that any use of chemicals or biological material as a weapon is completely inconsistent with international standards and norms regarding such capabilities," Baskey said.
--Richard Sisk can be reached at Richard.Sisk@military.com.