Anti-tank weapons that were likely once owned by moderate Syrian rebels have landed in the hands of Islamic State militants, according to a newly released field investigation conducted in both northern Iraq and Syria.

The Islamic State has also captured “significant quantities” of U.S.-manufactured small arms and has employed them on the battlefield, researchers found.

The investigation, led by a small-arms research organization known asConflict Armament Research, marks a rare attempt to physically document the weapons being used by the Islamic State, the radical group that has expanded its control in parts of Syria and Iraq. […]