The U.S. military’s Central Command admitted Friday that a Syrian fighter trained by U.S. forces handed over six vehicles and ammunition to an al Qaeda intermediary, “purportedly in exchange for safe passage within [his] operating area.”

It marks one of the first times the U.S. has admitted that its equipment had fallen into the jihadist group’s hands.

As recently as Wednesday, officials had said they were aware of where“100 percent” of the weapons were. As it turned out, a commander trained to fighters had already handed over the equipment to Jahbat al Nusra, an al Qaeda affiliate operating in parts of western Syria.

The missing equipment accounted for 25 percent of what was provided to a class of 71 U.S. trained fighters, U.S. Central Command said in a statement.

The announcement was the latest embarrassment for the already embattled train and equip program, which once aimed to train 5,400 fighters a year to confront the self-proclaimed Islamic State. Instead, last week CENTCOM commander Army Gen. Lloyd Austin admitted that only trained “four or five” fighters were in Syria, out of an initial class of 54 trainees.

Since Austin’s announcement, the Pentagon announced a second class of 71 fighters completed training and had entered Syria. The new class was supposed to be proof that the program was making progress. But Friday’s admission only reinforced fears the program was not working and that U.S. arms and equipment could into jihadist hands.

The lost equipment were issued to part of the class of 71 fighters, officials said.

Earlier this week, Jahbat al-Nusra, an al Qaeda affiliate, boasted both via social media and in an interview with The Daily Beast that the U.S.-provided arms were now in the hands of their jihadis. The weapons had been stolen by a commander affiliated with U.S. trained fighters, Anas Ibrahim Ubayad or Abu Zayd, after he reported defected, the group claimed.

U.S. officials said the fighter who handed the weapons over had received U.S. training and that Abu Zayd had not. CENTCOM refused to name the commander who handed over the equipment.

American officials conceded that their earlier claim that they could account for 100 percent of the weapons was based on assurances made by the U.S. trained fighters. The fighters have since retracted those claims. CENTCOM said it also is looking to track the equipment’s whereabouts.

The Pentagon believes all the fighters remain accounted for. U.S. officials had said they would not account for the fighters once they entered Syria.