As concerns grow of a potential war between the United States and Iran, experts told Newsweek that the U.S. military has used up parts of its stockpile in recent years but remains “powerful.”

Why It Matters

The relationship between the United States and Iran, long adversaries on the global stage, has been strained even further amid ongoing domestic protests against the Middle Eastern nation’s government. Massive demonstrations have erupted across the country in recent days, representing the most significant threat in years to the nation’s leadership.

The U.S. has not ruled out intervention, with President Donald Trump warning that Washington would take “strong action” if Iran executes protesters. The Wall Street Journal reported on Thursday that Trump has ordered military assets to be prepared for a potential strike against Iran.

As concerns of a conflict escalate, experts discussed the state of America’s weapons stockpile with Newsweek.

What To Know

For years, there have been concerns that the stockpile was dwindling as the U.S. provided weapons to Ukraine amid its war with Russia or Israel amid its conflict with Hamas. The U.S. has given allies a wide variety of weapons, including air defense systems and armored vehicles.

Washington has also sold a significant number of weapons to allies. In FY2024, the U.S. made $117.9 billion in military sales, according to the State Department.

Critics have raised concerns about whether that could deplete the weapons stockpile.

Defense Secretary Pete Hegseth in July 2025 paused weapons shipments to Ukraine amid worries over the stockpile, reported the Associated Press. The Pentagon found that stocks on some weapons were too low to ship abroad, while not specifying which ones.

The precise number of American weapons in the stockpile is classified information, but there are ways analysts can determine approximate figures. Jennifer Kavanagh, senior fellow and director of military analysis at Defense Priorities, told Newsweek that analysts can get a rough idea by analyzing data on the total number of weapons the U.S. has bought and used across conflicts, though that information is not always available.

“Some of that is intentional, you know, the more sensitive weapons are classified,” she said. “And some of it is just the messiness of defense budgeting and military operations.”

While there are no exact numbers, Kavanagh said, “with some certainty,” that the missile stockpiles are depleted at this point. There are multiple reasons behind this, including that they “were not that deep to start with.” Some of those munitions have been sent abroad or used by the U.S. during military operations against the Houthis in the Middle East or some of the activity in Latin America, Kavanagh added.

The rate at which some sensitive munitions have been used is “much faster” than the rate they can be replaced, she said. While contractors are working to ramp up their production capacity, there are concerns the military underestimated how much they have needed for global commitments.

The military still has the capacity to perform short operations that may not require as much weaponry, she said, but some more advanced ammunition can be replaced by cheaper, less precise weapons—as the most accurate ones aren’t always required.

The most extensive concerns swirl around air defense, according to Kavanagh. “There was a lot of surprise even among the military community about the amount of air defense that the United States went through in helping to protect both U.S. Forces and Israel during the Twelve-Day war this summer. And that was only a Twelve-Day War against Iran, which had a reasonable stockpile of missiles, but not of anything approaching China or Russia. And yet it still severely drained air defense stockpiles,” she said.

Mark Cancian, former Office of Management and Budget official who oversaw Department of Defense procurement, told Newsweek that the Ukraine war showed how “warfare requires many weapons to replace losses and equip new units.”

“Fighting also burns through immense amounts of munitions. This experience occurred at the same time that analysis of a possible US-China conflict showed a great demand for air and naval munitions, particularly air defense and long-range precision strike. One important anti-ship missile ran out in the first week,” he said.

The U.S. would be unlikely to lose many weapons such as aircraft in an Iran strike, Cancian added, but it would expend munitions such as long-range missiles. That wouldn’t necessarily spur immediate concern with Iran because inventories are “sufficient,” he said. “The concern is a future conflict with China, where the United States would need all its available munitions and more.”

Matthew Bunn, James R. Schlesinger professor of the practice of energy, national Security and foreign policy at Harvard University, told Newsweek that while some weapons are in short supply, others are “more or less in abundance.”

“What you need for a ‘smash and grab’ like the Maduro raid and what you need for destroying a deeply buried facility like the strikes this past summer are totally different. And what you would need for a prolonged war is totally different again,” he said.

While the U.S. has indeed “used up a lot of stuff,” the nation still has a “very powerful military remaining,” Bunn added.

The concerns about the Ukraine war are “mostly about weapons that wouldn’t be too relevant for this scenario, such as precision artillery shells,” he said, while agreeing that air missile defense interceptors could pose an issue.

“Iran would likely respond to any U.S. strikes with missile and drone strikes on Israel and US forces in the region, and a lot of interceptors in Israel and in U.S. regional forces got used up during the Twelve-Day War,” Bunn said, adding that “Ukraine wants more interceptors, U.S. allies in Europe want more, etc., and there’s a limit to how fast the companies can make them.”

The sort of operations the administration may be considering against Iran, which is farther away and better defended than Venezuela, remains unclear, he said. It would be “much more difficult” for a quick operation like the administration conducted against Venezuelan President Nicolás Maduro, he said.

Barry Posen, Ford international professor of political science at the Massachusetts Institute of Technology (MIT), told Newsweek it is plausible the U.S. may be short of “some of the newest and fanciest long range munitions.”

“When the US does these performative air strikes, it usually uses the very best to minimize the loss of a pilot, and to maximize success. And our leaders seem to find reasons to launch these strikes,” he said.

How Do the US, Iranian Stockpiles Compare?

Despite some concerns about some weapons being depleted, the stockpile remains “much deeper and better than Iran’s,” Kavanagh said.

During the conflict last summer, Iran expended many of its munitions, she added: “Definitely the United States has a better stockpile than Iran, but Iran has also a different strategy, which is I think what we saw during the Twelve-Day War. It was willing to just kind of fire missiles. It didn’t necessarily matter so much where they were targeted or where they hit like the idea was just to overwhelm Israel’s air defense and impose some kind of cost. That’s a very different strategy than the U.S. has.”

This means the air defense interceptor challenge is a legitimate concern, as any target may take a few of those interceptors, she said. Even a country with a smaller, less advanced arsenal could pose those challenges.

Cancian said the U.S. would have “overwhelming air and naval dominance,” though Iran’s large ground force would prevent the U.S. from engaging in a boots-on-the-ground operation without “huge preparation.”

Posen said that while the U.S. has a larger stockpile, Iran probably still has many missiles and rockets.

How Could US Prepare Stockpile for War?

The U.S. has taken steps to prepare the stockpile, according to Cancian. The U.S. began an effort to increase munition inventories during the Biden administration, and the reconciliation bill added “substantial funds.”

“The problem is that it takes time to rebuild inventories. Lead times for production run about two years,” he said.

Kavanagh said the best way to build up stockpiles is to “stop using them all the time.” No matter how many weapons a country produces, that will not refill stockpiles if they are burned through, she said.

“We should be much more discerning about the countries that we sell weapons to and the countries we give military assistance to, especially for munitions that are of high importance,” Kavanagh added.

What People Are Saying

Bunn, also to Newsweek: “I do think it makes a huge difference whether we’re doing sort of a one-off raid in the way that we did last summer or some more extended campaign, As you know, the Iraq war that President Trump has greatly criticized, went very well in the initial overthrowing of the dictator and then became a quagmire that costs trillions of dollars and many American lives and huge numbers of Iraqi lives, set the Middle East on fire and helped to lead to the rise of the Islamic State. So regime change is not an easy task, and it’s a task that carries enormous risk. And without UN authorization, it’s also illegal under international law for the United States to strike foreign countries militarily.”

Posen, also to Newsweek: “I doubt that the shortages are big enough to affect the initial stages of a war with Iran. If it were to go on for a while, that could change. Also, if you use your best to fight Iran, then you could be short in another contingency. That is always one of the major concerns. Do you have enough weapons for ALL the priority contingencies. As China gets more and more capable, the estimated number of high end systems needed to fight them will also go up, and thus the risk you assume by expending the same weapons on optional contingencies elsewhere goes up.”

White House press secretary Karoline Leavitt, to reporters: “All options remain on the table for the president.”

Abbas Araghchi, Iran’s foreign minister, to Fox News: “My message is: Between war and diplomacy, diplomacy is a better way, although we don’t have any positive experience from the United States. But still diplomacy is much better than war.”

What Happens Next

Tensions remain high between Washington and Tehran, and concerns of a wider conflict in the region are ongoing.