The U.S. military is raiding its smart-bomb stockpiles around the world to continue its nearly two-year-old airstrike campaign against the Islamic State in Iraq and Syria, Pentagon officials said.

Defense Department officials are trying to figure out “how we balance the weapons we have,” U.S. Air Force Lt. Gen. Charles Brown, the man overseeing the airstrikes, said Thursday.

“We have to do some analysis of where we take risk,” Brown said in a video conference with reporters from Al Udeid Air Base in Qatar, home to the American-run combined air and space operations center.

“What I mean by that is: where do we pull some weapons from that we were saving for other contingencies,” he said. “And do we use them now or do we save them for later?”

The coalition has conducted 12,453 airstrikes in Iraq and Syria since August 2014, according to Operation Inherent Resolve, the task force overseeing the counter-ISIS campaign. More than 8,500 of the strikes have occurred in Iraq and nearly 4,000 in Syria. American warplanes and drones alone have conducted 9,495 of the strikes, with allies accounting for the remaining 2,958. More than 41,697 bombs have been dropped in those strikes. And the U.S. has loaned bombs to allies participating in the strikes.

The bomb shortage could be further compounded by a Pentagon policy that would require it to ditch old cluster munitions, military officials said.

The U.S. maintains bomb stockpiles in Europe, the Middle East, and the Pacific. Many of these consist of older versions of modern bombs, according to a January Center for Strategic and International Studies review of U.S. defense strategy in the Pacific.

"Ideally [the Pentagon] would also procure large numbers of the most modern munitions," the report said. But spending reductions from the Budget Control Act "have affected all modernization, including munitions."

U.S. Defense Secretary Ash Carter announced in February that the Pentagon would ask Congress for more than $1.8 billion to buy 45,000 new bombs. U.S. arms makers have already increased bomb production to keep up with the demand.

The military is facing this shortfall because it did not forecast needing this many weapons three or more years ago when it made its budget projections. At the time, no U.S. forces were in Iraq and the military was preparing to withdraw from Afghanistan. But that didn’t happen; thousands of American forces remain in Afghanistan and thousands more have gone back to Iraq to train and advise the Iraqi military. Brown also pointed out that allies, in many cases, are dropping American-made, guided smart bombs.

“I know the Air Force has taken some steps to increase in the next [budget cycle], to buy more weapons,” Brown said. “[T]hose weapons are about two years or so away, if not more.”

The bomb shortfalls extend beyond U.S. Central Command. Adm. Harry Harris, the commander of U.S. Pacific Command, told Congress that he was also concerned about depletion of bomb stockpiles.

“Critical munitions shortfalls are a top priority and concern,” Harris wrote in testimony for a Feb. 23 Senate Armed Services Committee hearing. “USPACOM advocates for continued investment, additional procurement and improved munitions technologies to better deter and defeat aggression.”

Harris also wrote that PACOM needs “improvements in munitions technologies, production, and pre-positioning, but fiscal pressure places this at risk.”

In a previously unreported March 10 letter to House Armed Services Committee Chairman Mac Thornberry, R-Texas, Harris listed additional purchases of munitions in his top three unfunded priorities. The admiral singled out AIM-9X and AIM-120D air-to-air missiles, SM-6 surface-to-air missiles and MK-48 torpedos. All four weapons are made by Raytheon.

The CSIS report recommends the Pentagon deploy more bombs to Guam, Japan and Korea.

At a March 22 House Armed Services Committee hearing, Gen. Joseph Dunford, chairman of the Joint Chiefs of Staff, said it would be “several years before we fully restore full-spectrum readiness across the services and replenish our stocks of critical precision munitions.”

Cluster Weapons

In February, Gen. Curtis Scaparrotti, then-commander of U.S. Forces Korea, warned that the loss of cluster bombs could deplete the U.S. military’s stockpile in the Pacific.

“[W]e must maintain an adequate quantity of critical munitions to ensure alliance supremacy in the early days of conflict on the Peninsula,” Scaparrotti said at a Feb. 24 House Armed Services Committee hearing.

The general said the problem is “further amplified by the approaching loss of cluster munitions due to shelf life expiration and the impending ban.”

In 2008, then-Defense Secretary Robert Gates placed restrictions on the stockpiling and use of cluster munitions, even though the U.S. is not a signatory to the Convention on Cluster Munitions.

The Gates policy, which goes into effect in 2019, states that “the use of cluster munitions that have a dud rate of greater than one percent can no longer be a part of our inventory and be employed,” Scaparrotti said at the Feb. 23 Senate Armed Services Committee hearing. “I rely on cluster munitions in a very large way to affect operations if we go to crisis on the Peninsula.”

“My concern is, that we will not be able to replace those cluster munitions with proper munitions or we'll use unitary rounds which … have the same effect,” he said. “I have to fire three to five rounds for each one of those cluster munitions.”

The Senate version of the 2017 National Defense Authorization Act prohibits the Defense Department from destroying any cluster bombs until the defense secretary provides lawmakers with the Pentagon’s policy on the weapons. Sen. Tom Cotton, R-Ark., inserted the language into the bill.

The bill would also allow the Pentagon to set up a special budget account with up to $1 billion to buy and stock “precision guided munitions anticipated to be needed by partner and allied forces to enhance the effectiveness of overseas contingency operations conducted or supported by the United States.” Cotton worked on this language with Senate Armed Services Committee Chairman John McCain, R-Ariz.