U.S. stockpiles of critical air defense interceptors have been dramatically reduced by an estimated 65% since combat between the U.S. and Iran escalated on Feb. 28, according to a report released this week by the Center for Strategic and International Studies (CSIS).
The report, titled "Renewed Iran War Would Test Diminished Interceptor Inventories," updates an earlier assessment from April 8, following a temporary ceasefire. The U.S. and Iran have exchanged fire intermittently in recent weeks after a memorandum of understanding for a ceasefire collapsed.
The initial CSIS report in April estimated a 55% decrease in U.S. Patriot interceptor stockpiles. The updated figures, which account for engagements since the April ceasefire, indicate a further 10% reduction, bringing the total loss to approximately 65%.
This leaves the U.S. with an estimated 759 of its highest-end Patriot missiles, the analysis states. Production of these interceptors stands at 183 per year, with a lead time of about 3.5 years from contract signing to delivery.
Stockpiles of THAAD interceptors, a longer-range and higher-altitude air defense system, have remained stable since the April ceasefire. However, during combat between Feb. 28 and April 8, U.S. THAAD interceptor stocks were roughly halved. Experts identify THAADs as the most challenging air defense munition to replace.
CSIS based its findings on data from Gulf countries and public congressional and Pentagon budget documents to appraise U.S. stockpile levels and usage.
The Pentagon has requested $67 billion in supplemental funding from Congress, part of which is intended to address munitions shortfalls. Defense Secretary Pete Hegseth has stated that the current administration inherited insufficient inventories, citing arms transfers to Ukraine by the Biden administration that were not replaced.
During the Biden administration, three Patriot missile batteries were provided to Ukraine from U.S. stockpiles under the Presidential Drawdown Authority, though it remains unclear if this directly impacted U.S. Patriot battery and missile capability.
In response to inquiries, Pentagon spokesman Sean Parnell stated that the U.S. "has everything it needs to execute" the president's orders and that the military maintains a substantial arsenal to protect national interests.
Retired Marine Corps Col. Steve Ganyard, an ABC News contributor, described the munitions shortages as a "very serious situation" that will not be resolved quickly. He noted that the industrial base cannot keep pace with the rate at which interceptors are being expended, with some missiles requiring two to four years for production and delivery.
This situation could have strategic implications. Ganyard suggested that adversaries like China might view the rapid depletion of U.S. missile stockpiles as an opportune moment to make aggressive moves, such as an invasion of Taiwan.
In response to the strain on resources, U.S. Pacific Air Forces is considering reducing upcoming exercises in the region to ensure the Air Force can provide options for other global theaters. General Kevin Schneider, commander of Pacific Air Forces, indicated that exercises would be re-evaluated based on their importance for force readiness.
"I think we’ve done a pretty good job of identifying, amongst commanders, where we’re going to take risk or how we manage the risks as we prioritize efforts in Central Command region right now," Schneider said.