Arms supplied by the United States to Syrian rebels under the Obama administration were regularly captured by the Islamic State and used against American-led coalition forces, according to an international arms monitoring group.
The London-based Conflict Armament Research (CAR) disclosed in its latest report that most of the arms recovered from ISIS were stolen in bulk from the Iraqi and Syrian militaries during initial advances by the militant group in 2014. But many of the group's weapons, particularly newly manufactured ammunition, were initially provided by the United States and Saudi Arabia to Syrian opposition forces battling President Bashar al Assad.
The report detailed a dozen cases in which arms purchased by the U.S. for Syrian rebels ended up in ISIS's arsenal. In one instance, it took militants less than two months to capture a guided antitank missile bought by the Pentagon from Bulgaria and supplied to a Syrian opposition group.
The occurrence demonstrates the swiftness in which U.S.-supplied weapons can be turned against its own troops and allies.
"These findings are a stark reminder of the contradictions inherent in supplying weapons into armed conflicts in which multiple competing and overlapping non-state armed groups operate," the report said. CAR later noted that international efforts to supply weapons to rebel groups "have significantly augmented the quantity and quality of weapons available to [ISIS] forces."
Investigators were unable to determine whether the 40,000 weapons recovered from ISIS over the past three years were captured on the battlefield or acquired from Syrian rebels amid ever-changing alliances.
The Obama administration began covertly supplying weapons to moderate Syrian rebel groups in 2013 to combat the Assad regime. President Donald Trump ended the secretive CIA operation in July, but a publicly known federal program to arm the Syrian Democratic Forces against ISIS remains in place.
The report found no evidence of SDF weapons falling into the hands of ISIS.
CAR said all of the weapons purchased by the United States were manufactured in European Union states, raising the prospect that the Pentagon violated international contracts.
"At the very least, the diversion of weapons documented in this report has eroded the trust that exporting authorities placed in the recipient governments," the authors wrote. "At worst, the diversions occurred in violation of signed agreements that commit recipient governments not to retransfer materiel without the exporter's prior consent."
Though the terrorist group often showcased American-made weapons presumably seized from Iraqi security forces in its propaganda videos, the majority of arms captured by ISIS came from Russia and China.
Roughly 90 percent of weapons and ammunition deployed by ISIS were manufactured in China, Russia, and Eastern European countries, with Moscow and Beijing accounting for more than 50 percent, according to the report. By comparison, NATO-produced weapons and ammunition accounted for 3 percent and 13 percent of ISIS's arsenal, respectively.