‘Race of attrition’: US military’s finite interceptor stockpile is being tested
The U.S. military’s increased use of missile interceptors during the war with Iran poses long-term strategic risks to integral defense capabilities if fighting spills into a long term conflict, experts caution.
Military Times spoke with several national security specialists, defense analysts and foreign policy pundits who warned that the U.S. military’s finite interceptor stockpile could be strained and potentially exhausted if the ever-changing projected timeline of Operation Epic Fury depletes a resource that cannot be replenished at the scale and pace of war.
“You can’t replace those kinds of missiles overnight,” said Kelly Grieco, a senior fellow at the Stimson Center, a nonpartisan Washington think tank. “It would take years.”
The U.S. currently employs several systems designed to destroy incoming missiles and drones, including the Patriot missile defense system, Aegis Combat System (SM-3/SM-6) and Terminal High Altitude Area Defense (THAAD) anti-ballistic missile systems.
As of December 2025, the Missile Defense Agency’s arsenal of SM-3s was 414 and the number of THAAD interceptors was 534, according to the Center for Strategic and International Studies.
Conversely, the Pentagon was receiving nearly 270 Patriot Advanced Capability-3 Missile Segment Enhancement per year since 2015.
That number has begun to climb, meanwhile, with Lockheed Martin in January agreeing to a seven-year deal with the U.S. government to produce approximately 2,000 PAC-3 missiles per year.
“Lockheed Martin is well-positioned to fulfill this agreement, having recently increased PAC-3 MSE production by more than 60% over the past two years,” the company announced in January. “In 2025, Lockheed Martin delivered more than 600 PAC-3 MSEs, a 20% increase from the previous year.”
But SM-3s and THAADS, known as ballistic missile defense unique interceptors, are the most adept at air-defense against incoming munitions, according to CSIS. As a result, they cost more and take longer to manufacture.
Though the exact number of interceptors used by the U.S. military during the first six days of Operation Epic Fury has not been released by the Defense Department, Grieco said it was likely not an insignificant amount, stressing that the resource was limited.
The U.S. likely used between 100 and 150 THAAD interceptors and 80 SM-3s in support of Israel during its Twelve-Day War with Iran and an unknown number of Patriot interceptors in Qatar to defend Al Udeid Air Base from Iranian attacks, according to CSIS.
More than 150 THAAD interceptors would equate to roughly 30% of the THAAD stockpile, which is “concerning,” CSIS said.
If the U.S. used interceptors during the current Iran war at the same rate it did during the Twelve-Day War, it would use half of its entire interceptor stockpile in four to five weeks, according to Grieco.
Israeli officials assessed that Iran possessed 1,500 missiles and 200 launchers at the end of that war, according to Iran Watch, a website published by The Wisconsin Project on Nuclear Arms Control that tracks Iran’s missile capabilities.
Their capabilities grew in the months that followed, with Iran reportedly possessing roughly 2,500 projectiles as of March 1.
But if the U.S. does dip that far into their interceptor stockpile, it would likely require interceptors from other theaters to be moved to CENTCOM, stripping U.S. military assets bare in those other areas of operations.
If the Iran war bled into multiple months and the U.S. interceptor usage rate was similar to that of the 12-day war, the U.S. could hypothetically deplete its entire interceptor stockpile, Grieco said.
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Before that would even happen, however, U.S. military forces would have to transition away from attempting to intercept everything.
Resources stretched thin
Six U.S. service members died Sunday when their makeshift operations center at a civilian port in Kuwait was struck by a suicide drone.
The missed opportunity for air-defense was the result of interceptor resources being stressed, said Daniel Shapiro, a fellow at the Atlantic Council who served in the Obama administration as the U.S. ambassador to Israel for six years.
“If there was nothing deployed, that obviously contributed because what resources we had, had to be deployed elsewhere,” Shapiro said. “If it was deployed, it was unsuccessful.”
In addition to the PAC-3 production contract, the Defense Department reached an agreement with Lockheed Martin in January to quadruple the yearly production of THAAD interceptors from 96 to 400.
But this isn’t something that will happen instantaneously. The PAC-3 agreement, for instance, is slated to ramp up over a span of seven years.
At this time, the U.S. military cannot immediately increase the number of interceptors by a vast margin.
“The Department of Defense is really good, but magic is still not one of its capabilities,” Grieco said.
The Trump administration is scrambling to replenish munitions resources and will host a meeting Friday with Lockheed Martin, RTX, L3Harris and other defense firm executives to discuss an uptick in missile systems production to replenish munitions used in the Iran war.
Stress on resources could also factor into the timeline for the conflict.
A dwindling amount of interceptors may have led to the end of the Twelve-Day War, according to Shapiro. So many interceptors were used during that time that the U.S. and Israel were approaching interceptor inventory strain, he noted.
“My understanding was that had the conflict continued for another few days or another week or so, it could have become critical,” Shapiro said.
The volume of ballistic missiles Iran has fired from the first day of Operation Epic Fury has decreased by 90%, CENTCOM commander Adm. Brad Cooper said during a media briefing at MacDill Air Force Base Thursday. Iranian drone attacks had also decreased by 83% since day one, he added.
The drop in Iran’s rate of firing projectiles possibly means that the U.S. offensive against Iranian missile capabilities and missile storage facilities is working. At this time, however, that remains unclear.
Dr. Sanam Vakil, director of the Middle East and North Africa Program at Chatham House, said during an Atlantic Council Thursday roundtable that the calculus regarding Iran was unknown.
“Certainly on day six, it looks like its capability to launch missiles is maybe reduced, but it could also be deliberate,” Vakil said. “Iran is prepared for a longer war than I think the U.S. administration clearly calculated for.”
Iran could either be conserving missiles to distract with multiple attacks in different domains or preparing for a military campaign that will come in waves, she said, or both.
Who can outlast?
The question is whether Iran can continue its barrage of ballistic missiles and drones and outlast the interceptor stockpile the U.S. has.
The Pentagon continues to provide assurances that Iran is not capable of this feat.
“We’ve got no shortage of munitions,” Defense Secretary Pete Hegseth said at MacDill Air Force Base Thursday.
Cooper said U.S. combat power continues to escalate while Iran’s is in decline.
And Chairman of the Joint Chiefs of Staff Gen. Dan Caine, who spoke at a Pentagon briefing Wednesday, addressed concerns regarding specific U.S. munitions shortages.
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“We have sufficient precision munitions for the task at hand, both on the offense and defense,” Caine said. “But I want to tell you, teammates, as a matter of practice, I don’t want to be talking about quantities.”
Despite the confidence military officials have projected, Hegseth and Caine reportedly admitted during a briefing with lawmakers Tuesday that Iran’s Shahed drones presented a problem for interceptors because they fly at a low altitude and can evade air defense systems, according to CNN.
And Iran has no shortage of the unmanned aerial vehicles — reportedly producing 10,000 per month, according to Reuters.
The drones are also cheap to manufacture, costing between $20,000 and $50,000, according to Open Source Munitions Portal, an online munitions archive run by a non-profit watchdog.
Contrast the $35,000 average cost of an Iranian Shahed drone with an estimated $4 million price tag of a PAC-3, and the cost exchange is 114-1 in favor of Iran.
Aside from missile math, the unknown timeline for Operation Epic Fury also factors in.
President Trump said this week that the military campaign could last four to five weeks, but that the U.S. had the capabilities to go far longer than that.
Hegseth, during a Pentagon briefing Wednesday, implied that the war could stretch up to two months, but reiterated the president’s point that the U.S. has enough munitions and equipment to beat Iran.
A U.S. CENTCOM memo obtained by Politico, meanwhile, detailed that the Pentagon was requesting military intelligence officers to be sent to its headquarters “to support operations against Iran for at least 100 days but likely through September.”
“The question is which clock will run first,” said Mohammed Soliman, a senior fellow at the Washington think tank the Middle East Institute.
Soliman said that any boots on the ground, including Kurdish allies, has the potential to prolong the conflict, leading to potential U.S. interceptor depletion.
Shortly after Military Times spoke with Soliman, reports emerged that pro-American, Iranian Kurdish forces had been supplied with arms by the CIA and were preparing to attack Iran.
The stress on the interceptor stockpile also depended on the endgame, according to Shalom Lipner, senior fellow at the Atlantic Council who served for over 25 years in the prime minister’s office in Jerusalem.
“It’s a race of attrition between the two sides to see who can get over the finish line before the other,” Lipner said.
Sen. Mark Kelly, a member of the Senate Armed Services Committee, raised concerns over the lopsided interceptor expenses during an interview with CNN.
“We can deal with some of this, but if they have more offensive assets than we have defensive, we get into trouble here possibly really quickly if our magazine depth goes to zero and they can then shoot these things freely around the region,” Kelly said.
The United States launched Operation Epic Fury on Feb. 28, killing Iran’s supreme leader Ayatollah Ali Khamenei during the initial attack, leaving a vacuum of power that has yet to be filled, though Khamenei’s son is an early favorite to succeed him.
The Trump administration has laid out select objectives for the operation, including the decimation of Iran’s missile capabilities, navy and its nuclear program.
On Tuesday, Cooper announced on X that the U.S. military had struck nearly 2,000 targets, with more than 2,000 munitions. In retaliation, Cooper noted, Iran has launched over 500 ballistic missiles and over 2,000 drones.
The admiral added Thursday that the U.S. has destroyed 30 Iranian navy vessels, including one off the coast of Sri Lanka — in the U.S. Indo-Pacific Command area of responsibility — that was the result of the first U.S. Navy submarine torpedo kill since World War II.
A total of 50,000 U.S. troops, 200 fighter jets, two aircraft carriers and bombers are currently stationed in the theatre, with personnel and ordnance reinforcement on their way, Cooper said.
Hegseth reiterated that during the press conference Thursday, saying the amount of firepower surrounding Iran is about to “surge dramatically.”
“We’ve only just begun to fight, and fight decisively,” he said.
Ella Rae Greene, Editor In Chief
