The Pentagon announced in December it was unable to send more weapons and munitions to Ukraine because Congress had not authorized more spending. Now it says there’s a $10 billion shortfall stopping it from replenishing the U.S. stockpiles, Politico reported.

“The deficit stems from the difference in the value of the equipment sent to Ukraine compared to the cost to replace it,” the article noted. “For example, if the Army sends older munitions that are no longer being produced, it might replace them with a newer version that is more expensive.

President Biden asked for additional funds in his supplemental spending request that has been stuck on Capitol Hill for months.

“We have not been able to, with the funding we have to date — and there’s a big funding piece waiting in the supplemental — replenish everything we’ve already given to Ukraine,” A DOD official told reporters. “So it would come back on our own readiness on our own stockpile to a certain extent if we can’t get new funding.”

Air Force photo by Senior Airman Jonathon Carnell