Share and Follow
(The Hill) If the U.S. engagement with Iran extends beyond the four to five weeks outlined by President Trump, the nation may experience pressure on its munition reserves.
The Trump administration has announced that a major offensive against Iran is imminent. On Tuesday, Trump assured that the U.S. has the capability to sustain wars indefinitely with its present arsenal, describing it as “virtually unlimited.”
However, experts question the president’s confidence, noting that prolonged conflict could lead to shortages of precision and high-tech munitions, as well as interceptors.
Joe Costa, director of the Forward Defense program at the Atlantic Council, highlighted the significant resource expenditure by the U.S. military. This includes the use of Terminal High Altitude Area Defense (THAAD) and Patriot interceptors, Advanced Medium-Range Air-to-Air Missiles (AMRAAM), and ship-launched missiles like the SM-2, SM-3, and SM-6.
“The strain on our interceptor capabilities could become a serious concern if we maintain this operational pace over an extended period,” said Costa, who formerly advised Pentagon leaders on war planning and overseas military deployment.
Joe Costa, the director of the Forward Defense program at the Atlantic Council think tank, said the U.S. military is expending a significant amount of resources, including Terminal High Altitude Area Defense (THAAD) and Patriot interceptors, the Advanced Medium-Range Air-to-Air Missile (AMRAAM), and ship-launched missiles such as SM-2, SM-3 and SM-6.
“I think it is very concerning in terms of the strain that this could put on our interceptor capacity if we maintain this sustained tempo over time,” said Costa, who previously served as the principal civilian advisor to Pentagon leadership for operational war planning and overseas force posture.
“Timelines are difficult without perfect information, but you’re talking weeks, not months,” he added.
Trump on his Truth Social platform declared that U.S. munitions stockpiles of so-called medium and upper medium grade weapons have “never been higher or better,” and that he was told the armed forces “have a virtually unlimited supply of these weapons.”
“Wars can be fought ‘forever,’ and very successfully, using just these supplies (which are better than other countries finest arms!),” he wrote. “At the highest end, we have a good supply, but are not where we want to be. Much additional high grade weaponry is stored for us in outlying countries.”
But the U.S. has still not resupplied high-end interceptors such as THAAD missiles critical in defending U.S. military personnel against Iranian ballistic missiles after the military blew through 25 percent of its stockpile over just a few days of operations against Iran in June 2025.
THAAD interceptors and Patriot missile systems have also been used extensively in operations in the Middle East, and Patriot missiles continue to be requested by Ukraine in its war with Russia.
Because of the weapons’ complex and high-tech makeup, as well as production constraints, each replacement missile can take upwards of two years or more to make. Due to this, the U.S. currently can produce only several hundred THAAD and Patriot missiles each year.
“Our production line is small enough that those won’t have been fully replenished since then,” Joel Rayburn, a senior fellow in Hudson Institute’s Center for Peace and Security in the Middle East, said of the THAAD missiles expended last year.
But Rayburn had a more optimistic view of the U.S. position in the war, telling The Hill: “I think the missile math favors us” due to Tehran’s own limited arsenal.
“The Iranian regime has already lost control of its airspace. . . . They’re not going to be spending, procuring or producing anything, because they’re under enemy fire. So whatever they have is what they’re going to expend. They can’t resupply themselves,” he said.
Still, Rayburn said expending too many munitions in the conflict with Iran could prove problematic for America’s future preparedness.
“Strategically beyond this conflict, it’s an issue for us, because if we have other contingencies that we need to have munitions planned for, and we’re expending a lot of the critically rare munitions here, then you know we’re going to have to have a strategy to account for that,” he said.
Other standard missiles that have been rapidly consumed are the Navy’s ship-launched SM-2, SM-3 and SM-6 munitions. The missiles have been used to protect vessels in the Red Sea against the Houthis, an Iranian-proxy group in Yemen, as well as to defend Israel from Iranian ballistic missiles.
The shortages have been so acutely felt that the Pentagon last year requested nearly $30 billion from Congress to backfill its high-end missiles and interceptors, but that request was only partially fulfilled in the Defense Department’s budget passed last month, The Washington Post reported.
Costa said in this instance, the U.S. needs to strike enough Iranian launchers and missiles so that they will then not be able to fire at American troops or interests, thus slowing down the number of interceptors it needs to launch.
“It’s a numbers game,” he said. “In that case, we can sort of slow down the expenditure rate. But if this goes on at this sort of tempo where we’re firing this many of these things, I would say that we would get quite concerned.”
The U.S. military also has more to worry about than Iranian missiles. Drone interception is quickly becoming a problem in the fight, as the low-cost threat can burn through costly, finite munitions and expose bases, ports, and critical infrastructure when defenses get saturated. It was a drone attack that led to the death of six U.S. service members on Sunday in Kuwait.
Making things harder to predict, Trump administration officials have offered differing timelines for how long the conflict is expected to last. The president has said the war was expected to last four to five weeks, but could go “far longer.”
Defense Secretary Pete Hegseth on Monday said Trump “has all the latitude in the world to talk about how long it may or may not take four weeks, two weeks, six weeks. It could move up, it could move back.”
And Vice President Vance said Monday that Trump will not stop the attack on Iran until he accomplishes four main objectives: Destroy Iranian offensive missiles, missile production, Tehran’s Navy, and ensure Iran will not have a nuclear weapon.
Prior to the operation, senior military officials reportedly made it known to Trump that a lack of critical munitions could hurt U.S. efforts to contain a possible Iranian retaliation.
Joint Chiefs of Staff Chairman Gen. Dan Caine voiced these concerns at a White House meeting last month with Trump and his top aides, warning that a major operation against Iran would face challenges from a significantly depleted U.S. munitions stockpile due to Washington’s ongoing defense of Israel and support for Ukraine, The Washington Post reported.
The question of weapons stockpiles has also worried lawmakers.
Asked Tuesday if he has concerns over stockpiles, Sen. Tim Sheehy (R-Mont.) replied: “Not tactically. On a strategic scale, absolutely.”
“I’m all about expanding our munitions production capacity to emphasize more on quantity instead of just quality,” he told reporters following an all-Senate classified briefing on Iran.
Sen. Tim Kaine (D-Va.) said “it’s a real issue that we have to pay attention to munitions, both offensive and kind of defense systems,” but that officials are “on it.”
“They know what the reserves and capacity are . . . it’s a backfill operation. That’s all I’ll say,” said Kaine.
Costa noted that previous administrations have decided against a war with Iran, recognizing the risk of being under-resourced should something unexpectedly break out, such as a Chinese assault on Taiwan.
“That’s why previous administrations have said it’s not worth it,” he said. “[The Trump administration] made a decision to say it’s worth it, and we’re banking on no other action to happen in the world.”