A new report finds a large percentage of the ammunition used by Islamic State militants in Iraq and Syria came from the United States. The London-based group Conflict Armament Research analyzed small-caliber ammunition recovered from the militants. While the cartridges it recovered originated in 21 countries, including China and Russia, nearly 20 percent of them came from the United States. The report states: “IS forces appear to have acquired a large part of their current arsenal from stocks seized from, or abandoned by, Iraqi defense and security forces. The U.S. gifted much of this materiel to Iraq.”