U.S.-trained rebels handed over American-supplied vehicles and ammunition to an al-Qaeda linked group shortly after arriving in Syria, the Pentagon said Friday, the latest blow to a Pentagon program that has been plagued by problems since its inception.

The rebels surrendered six pickup trucks and ammunition to an Nusra Front “intermediary,” the Pentagon said in a statement.The Nusra Front is an al-Qaeda affiliate in Syria.

The equipment was about one-quarter of what the group had been issued and was turned over the Nusra Front in exchange for safe passage through area controlled by the al-Qaeda affiliate.

The allegations, if true, would be “a violation of Syria train and equip program guidelines,” Col. Patrick Ryder, a spokesman for U.S. Central Command, said in the statement.

Pentagon officials initially denied media reports this week that the U.S.-backed rebels had turned over arms or equipment to the al-Qaeda affiliate. But on Friday they learned some of the allegations were true after U.S. backed rebels acknowledged it.