Seventy five Syrian rebels trained by the United States and its allies to fight ISIS have entered northern Syria.

U.S. military officials on Wednesday denied reports that the latest batch of American-trained Syrian rebels had defected to an Al-Qaeda affiliate.

The Pentagon is under intense scrutiny over its “train-and-equip” program in which moderate Syrian rebels are given instruction and weapons to fight Islamic State of Iraq and Syria (ISIS) militants in the war-torn country.

Several news and social media reports said the newest batch of about 70 rebels to graduate from the program — who were sent back to Syria last weekend — had defected to Al-Qaeda’s Syria affiliate, the Al-Nusra Front, then handed over their weapons.

“It’s patently false that there have been defections or weapons turned over… we believe the claims to those effect to be untrue,” Pentagon spokesman Captain Jeff Davis told reporters.

The program to train and arm moderate Syrian rebels to fight ISIS originally aimed to ready around 5,400 vetted fighters a year for three years.

But the pricey endeavor, which cost $500 million, got off to a disastrous start.

The first graduates, who made up a group of 54 fighters, were attacked by Al-Nusra in July and the Pentagon isn’t sure what happened to them all. At least one was killed.

A second setback would cause further embarrassment for America, but Davis stressed the new batch of fighters was not lost.

“We do have contact, we have communications with members of the group and our understanding from being in touch … is that all are present and accounted for, as are their weapons,” Davis said.

The program has also been hamstrung by a lack of suitable recruits who are able to pass the U.S. screening process.

Last week, before the insertion of the new fighters, the U.S. general overseeing efforts against ISIS drew disbelief from senior lawmakers when he told them only “four or five” U.S.-trained rebels were on the ground fighting in Syria.