U.S. defense officials have confirmed that military equipment issued by the United States to Syrian rebel fighters has been funneled to an al Qaeda offshoot, raising new questions about the ways in which the Obama administration is safeguarding U.S. arms in the war-torn Middle Eastern country.

A commander in the New Syrian Forces (NSF), a group being trained and equipped by the United States, was found to have distributed at least 25 percent of the force’s U.S.-provided hardware to the Nusra Front, a terrorist organization affiliated with al Qaeda.

The equipment, which included U.S.-issued ammunition and pick-up trucks, was "surrendered" to a Nusra Front affiliate in order to ensure that the rebel fighters could pass freely through territories controlled by the terrorist group, the Pentagon said.

A Syrian opposition commander who was leading a group of NSF recruits "self-reported to coalition forces that under threat from al Nusra, they surrendered six trucks and ammunition to a suspected al Nusra Front intermediary to secure safe passage after being told that unless he surrendered some of his NSF equipment, his unit would be ambushed en route to their new location," according to Col. Patrick Ryder, a spokesman for U.S. Central Command, who provided the Washington Free Beacon on Monday with a timeline of what took place.

"We will look at what we can do to prevent such a situation in the future, but given the complexity of the battlefield it is not possible to eliminate all risk," Ryder added. "We are using all means at our disposal to look into what exactly happened and determine the appropriate response."

The arms exchange occurred after a group of around 70 NSF graduates crossed into Syria on the morning of Sept. 20, according to the Pentagon.

The following day, the Syrian commander relocated the NSF fighters to a new location inside Syria.

"The [Syrian] commander began to relocate his NSF fighters to a different town," the Pentagon said. "According to information provided by the [Syrian] commander to the Coalition, he had been contacted by a suspected al Nusra Front intermediary and told that unless he surrendered some of his NSF equipment, his unit would be ambushed en route to the new location."

At that point, six vehicles were transferred to a Nusra Front intermediary. This commander later "provided a portion of the ammunition that had been issued to his NSF fighters to the suspected [Nusra Front] intermediary," the Pentagon said.

Ryder said that while U.S. and other collation forces do all they can to prevent this type of incident, they cannot "control every situation."

"The coalition’s train and equip program does everything possible to carefully screen participants in the program and to monitor their equipment," he said. "These standards are one of the reasons that we have only trained a small number of fighters to date."

However, "even with this screening and other precautions, we can’t control every situation that these fighters encounter once they return t‎o Syria," he added. "Syria is a very complicated battlefield with [the Islamic State], al Nusra, and the moderate and vetted opposition’s area of control frequently and sometimes quickly shifting. This is a battlefield situation in which the moderate and vetted opposition continues to face threats on multiple fronts, including from various extremist groups."

The United States remains "committed to strengthening and growing" opposition forces who can fight the Islamic State and other terror groups, Ryder said.

Rumors that U.S. equipment had fallen into the arms of the Nusra Front first emerged last week when the terrorist group tweeted what appeared to be a picture of U.S.-issued rifles that had previously been given to the NSF.

At the time, the Pentagon called the reports false. However, upon further investigation, officials determined that the NSF has in fact traded U.S. military hardware to the Nusra Front.

"In light of this new information, we wanted to ensure the public was informed as quickly as possible about the facts as we know them at this time," Ryder said in a separate statement issued over the weekend. "We are using all means at our disposal to look into what exactly happened and determine the appropriate response."