The Pentagon is preparing to ask Congress to approve spending $1 billion to replace weapons sent to Ukraine, a request that will essentially exhaust the “drawdown account” of funds available to replenish U.S. stockpiles.

“I don’t believe the final $1 billion request has quite gone over yet, but it’s, I believe, very close to going over,” Doug Bush, the Army’s assistant secretary for acquisition, logistics, and technology, said Thursday at the Defense One Acquisition Summit. 

Congress will have 15 days to approve or reject the request. Lawmakers have not rejected any of the administration’s drawdown requests to date, Bush said.

“Right now, [there’s] just under a billion. However, we’re working on using the remainder of that pending Congressional approval,” he said. “Pretty soon it’ll be zero.”

President Biden has asked Congress to approve $61.4 billion in new aid to Ukraine. Republicans have said they would approve the expenditure if it comes with new border security measures to reduce the flow of migrants across the U.S. border with Mexico. Senate Republicans on Wednesday blocked a bill that would provide aid to Ukraine and Israel because it did not include enough border measures.

Bill LaPlante, the Pentagon undersecretary for acquisition and sustainment, said there’s “fumes” left in the Ukraine drawdown account. 

“There’s already about four or five things that people want to spend it on,” LaPlante said Saturday at the Reagan National Defense Forum in Simi Valley, California. “Consider it gone, basically.”

Bush said the U.S. supply of weapons to Israel, including 155-millimeter artillery, in recent months has not affected the flow of weapons to Ukraine.

“That 155 provided to Israel was not going to Ukraine,” he said. “That came out of our stocks.”

Bush said the transfer of weapons to Israel has been done through a rapid foreign military sales package that allows the munitions to be transferred directly from U.S. military arsenals.

Weapons to Ukraine have been sent using a different mechanism called presidential drawdown authority.

“So far, there’s not been a lot of overlap” between Ukraine and Israel, Bush said. “We’ve done munitions of many types—everything from helicopters to artillery, some night vision—but nothing where it was so far, at least, a direct competition with what was already planning to go to Ukraine.”

He acknowledges that as the wars drag on, that might cease to be the case.