In this February 2022 photo, Ukrainian servicemen unpack Javelin anti-tank missiles, delivered as part of the United States of America's security assistance to Ukraine, at the Boryspil airport, outside Kyiv.
CNN  — 

The Pentagon did not properly track $1 billion worth of military equipment sent to Ukraine, according to a watchdog report released on Thursday.

The report from the Pentagon Inspector General says that while the Defense Department has improved its ability to track military aid sent to Ukraine, it “did not fully comply” with requirements and much of the equipment sent is “delinquent,” meaning it’s not possible to complete an inventory of everything sent.

Among the items that are designated for enhanced end-use monitoring (EEUM) are weapons like Javelin and Stinger missiles, night-vision devices, AIM-9X missiles, and Advanced Medium-Range Air-to-Air Missiles. According to the IG report, roughly $1.005 billion of the total $1.699 billion of equipment subject to end-use monitoring was not inventoried as of June 2023.

The new report comes at a critical moment for Ukraine aid, as Congress debates whether to authorize a supplemental package of more than $60 billion in aid amid significant Republican opposition. A failure to provide a new package could be damaging to Ukraine’s chances of winning the war after its counteroffensive against Russian forces stalled last year.

The report will likely buttress the stance of Republicans arguing against sending more aid.

Since December 2022, revisions to the inventory process for the Defense Department and Ukrainian Armed Forces resulted in an improvement to the Pentagon’s ability to track the weapons, the report says. But “significant personnel limitations and accountability challenges remain.”

“Until the DoD resolves these challenges, it will be unable to fully comply with the EEUM program requirements to account for all of the more than $1.699 billion in EEUM‑designated defense articles provided to Ukraine,” the inspector general said in its report.

Indeed, the US’ Office of Defense Cooperation (ODC)-Kyiv said there is “no evidence of unauthorized or illicit transfer of EEUM defense articles provided to Ukraine,” and emphasized personnel limitations as a primary challenge to providing a full inventory of equipment.

“Standard EEUM inventory procedures are not practical in a dynamic and hostile wartime environment,” a letter from ODC-Kyiv said, adding that the “unprecedented volume” of equipment being sent to Ukraine “is beyond the capacity of the limited DoD personnel in country to physically inventory even if access were unrestricted.”

Pentagon spokesman Maj. Gen. Pat Ryder said later on Thursday that there is “no credible evidence of illicit diversion of US-provided advanced conventional weapons from Ukraine.”

“We do see some instances of Russia continuing to spread disinformation to the contrary, but the fact is, we observe the Ukrainians employing these capabilities on the battlefield,” Ryder said. “We’re seeing them use them effectively, for all the obvious reasons in that Russia continues to present a significant threat to Ukraine’s sovereignty.”

While delinquency could suggest weapons had been stolen or diverted away from Ukrainian forces, the inspector general said it was outside the scope of its probe to determine what had happened to the weapons that were not properly tracked.

“The DoD OIG now has personnel stationed in Ukraine,” the report says, “and the DoD OIG’s Defense Criminal Investigative Service continues to investigate allegations of criminal conduct with regard to U.S. security assistance to Ukraine.”