On Tuesday, CNN reported that a wide assortment of US-supplied weapons ended up for sale on an online terrorist marketplace in Syria.
"DoD conducts vetting of all recipients of assistance," Pahon said on Wednesday. "DoD conducts vetting of partner forces prior to issuing equipment and carries out end-use monitoring of issued equipment."
The Defense Department, he added, ensures the recipients uphold international law are focused on fighting Daesh rather than the Syrian government.
"DoD provides assistance incrementally and the amount is metered to the minimum needed for the immediate mission," Pahon said.
In December, the Conflict Armament Research (CAR) center, an international arms monitor, has reported that US military weapons that were covertly provided to Syrian opposition groups were in the hands of Daesh within two months of their delivery.