CNAS Insights | Can the United States Sustain Its War Against Iran?

As Operation Epic Fury nears its one-week mark, the Trump administration is preparing to host U.S. defense companies at the White House for a discussion on defense production. At the center of ongoing operations are questions surrounding munitions supplies and strains on the systems that deliver them. How could munitions constraints limit the ongoing campaign against Iran? How quickly can industry replenish what’s been expended? What do these expenditure and replenishment rates mean for America’s ability to respond to crises elsewhere?

At this stage, Operation Epic Fury is a military success funded by strategic risk. While direct-attack weapons are plentiful, the conflict is steadily draining the scarce munitions—standoff, antiship, air defense, and counter-drone—that the United States would need most in a war with China. To credibly deter Beijing, the United States will need dramatically larger inventories and fresher forces than it had even before Epic Fury. U.S. progress in its operational goals against Iran comes at the expense of precious munitions and strategic assets, namely ships, tankers, and carrier strike groups, which are absorbing deployments that will leave lasting readiness gaps. In some areas, production is ramping up, but structural constraints remain and the most critical stockpiles and platforms will take years to build. Every additional week at high tempo deepens a deficit that the industrial base cannot quickly erase.

Where the United States Is in Good Shape and Where the Picture Gets Worse

First, the good news. The United States possesses deep stockpiles of short-range direct-attack weapons—joint direct attack munitions, small diameter bomb I/IIs, Hellfires—that are well suited to striking land targets in Iran under permissive conditions. Where Iran’s air defenses are neutralized, U.S. aircraft will be able to fly close enough to their targets to employ these weapons effectively. With hundreds of thousands of direct-attack munitions, U.S. forces could continue to levy attacks on Iranian targets for an extended period, so long as U.S. air superiority permits. According to recent statements, U.S. forces are beginning to make this “transition” to stand-in munitions, though recent reports indicate long-range standoff munitions are still being employed for certain missions.

Other important weapons categories are in shorter supply, have been heavily expended, and may still be needed. Crucially, these weapons will also be in the highest demand in an Indo-Pacific conflict. In four critical munitions categories, the Iran campaign is drawing down stockpiles that would be indispensable in the Pacific.

Long-Range Standoff Weapons

Tomahawk and joint air-to-surface standoff missiles (JASSMs) are in far more limited supply and production has recently thinned. In recent years, the Navy has procured very few land-attack Tomahawks, even as forces fired them at hundreds of targets. JASSM are likely in even shorter supply. The Joint Force has sufficient reserves of these weapons for an extended campaign against Iran. But it has never had sufficient stockpiles for a high-intensity fight with a near-peer adversary like China, whose military targets are exponentially more numerous, more difficult to strike, and can reconstitute more quickly.

Antiship Weapons

The United States largely abandoned the maritime strike mission after the Cold War and is only now rebuilding capacity. Fortunately, Iran’s navy is small, but unfortunately, so is the U.S. inventory of maritime-strike tomahawks (MST) and long-range antiship missiles (LRASM). Although a U.S. attack submarine sank an Iranian frigate in the Indian Ocean using a heavyweight Mk-48 torpedo, a first since World War II, this milestone underscores a deeper vulnerability: Heavyweight torpedoes remain in dangerously short supply relative to the demands of a potential conflict with China, which fields the world’s largest naval force, supplemented by thousands of maritime militia and coast guard vessels. This combined force would rapidly outstrip existing U.S. maritime strike inventories.

Air Defense Interceptors

These are among the most significant constraints. Surface-to-air missiles are expensive, which has limited stockpile size, and they have already been substantially depleted defending Israel and ships in the Red Sea. Additionally, the United States does not have enough launchers to cover all potential targets. The United States is almost certainly conserving these high-end weapons for ballistic missiles, which Iran fired by the hundreds in the opening days of the conflict. Since then, however, Tehran’s ballistic missile strikes have tapered off significantly, suggesting either a depleted stockpile, a deliberate shift in strategy, or being pinned into underground shelters by U.S. aircraft. The Joint Force should be mindful of the lessons it draws from this early success. Interceptors will be at an even greater premium in a conflict against China, whose missile forces dwarf Iran’s in both scale and sophistication, and, as discussed below, Iran’s missiles may yet mount a comeback.

Counter–uncrewed aerial system (C-UAS) weapons.

Iran has doubled down on cheap drones to strike both civilian and military targets. This threat requires ground-based point defenses, such as the Army’s LIDS/Coyote system, to be positioned at every priority location, driving up demand for both launchers and interceptors. The Air Force has turned to advanced precision kill weapon system (APKWS) guided rockets as an airborne C-UAS solution, but procurement of purpose-built variants remains strikingly limited—just 340 roundslast year. The scarcity is already forcing hard tradeoffs: Last year, a shipment of APKWS rockets originally bound for Ukraine was divertedto the Middle East to meet urgent demand. These capabilities hold promise but have not yet achieved the scale necessary to fend off Iranian Shahed strikes, much less People’s Liberation Army drone swarms. Additional passive defenses, particularly hardened structures, could offer meaningful protection against the smaller payloads drones carry. Had such measures been in place, the tragic loss of life at the U.S. base in Kuwait might well have been prevented.

The Replenishment Challenge

Efforts to expand munitions manufacturing capacity are already underway. The Biden administration started multiyear procurement contracts for several key weapons, and the Trump administration has expanded these significantly. But new production takes time to reach the warfighter.

The deeper structural problem is that U.S. munitions production has historically been wildly inconsistent, and this has constrained the industrial base. The volatile annual budget cycle encourages short-term thinking, and munitions are perennially treated as the “bill payer”—cut one year with the promise of buying more the next. The result: The United States has never built and sustained the stockpiles it would need for a high-end fight against China.

The fragility of the industrial base compounds the problem. Prime contractors typically purchase materials year-to-year in step with congressional funding cycles, effectively pushing the Department of Defense’s demand volatility down through the entire supply chain. At the foundation of that chain sit small, sometimes single source subtier suppliers, and these companies possess little surge capacity and thin financial margins to absorb sharp changes in demand. When one of these suppliers closes its doors or its materials become obsolete, recertification processes can take years. When one receives a massive new order, scaling up is both a near-term challenge and a long-term business risk, since today’s surge order may become next year’s budget cut. It is these subtier business economics—not the capacity of the primes—that most often determine the ceiling on production rates.

Industry can sometimes accelerate production of existing weapons, but it takes extraordinary effort—and for high-end, complex munitions, there are hard limits. One former defense acquisition official noted that production increases typically take 12–18 months before they start generating large volumes.

How fast the United States burns through its most valuable munitions depends on the operation’s duration and intensity. The tempo so far—1,000 U.S. sorties on the first day alone, and 2,000 weapons employed in the first three days—more closely resembles the opening weeks of Desert Storm or the 2003 invasion of Iraq than the Balkans operations, Libya, or the fight against ISIS. The open questions are whether this pace can be sustained, whether U.S. interceptors can outlast Iran’s supply of drones and missiles, and what will be left in the U.S. inventory when it’s over.

The Enabler Gap: Mobility and Tankers

Beyond munitions, limited tanker capacity may place additional constraints on U.S. operations. Aircraft operating from distant bases require multiple refuels to reach their targets, and the hunt for mobile Iranian missile and drone launchers demands extended loiter time that burns fuel at a punishing rate. Yet this is a fraction of what a Pacific conflict would require, as the theater’s vast distances and more challenging air defenses would increase refueling, airlift, and logistics requirements by orders of magnitude. Every flight hour over Iran accelerates wear on an aging mobility fleet, eroding readiness that cannot be quickly restored. The longer Epic Fury runs at high tempo, the fewer options the United States will have not only to sustain the current campaign, but for deterring China.

Uncertain Futures

The campaign against Iran has been a striking tactical and operational success. But wars have a way of expanding, and several near-term scenarios could sharply increase the burden on U.S. forces. If the U.S. Navy takes on convoy escort duties through the Strait of Hormuz, demand for air defenses and tanker sorties to support defensive combat air patrols will climb steeply, while air defense destroyers and cruisers pulled to shield shipping lanes will leave other targets exposed. Already, the strain on the tanker fleet is acute and the surface Navy is being stretched thin. The Ford carrier strike group may be on track for a record 11-month deployment.

If U.S. forces struggle to achieve consistent air superiority, standoff munitions expenditure is not likely to decline and aircraft losses may mount. Additionally, if U.S. forces are called on to conduct noncombatant evacuation operations, U.S. air mobility assets and air defenses will face additional strain. Surges in flight hours will drive further maintenance demands across an already stretched fleet.

An Iran pivot from large scale barrages to precision “sniping”—opportunistically picking off targets rather than saturating defenses—would not end the attrition, but rather slow it, grinding through interceptors and defensive air patrols over weeks, while strike operations work to find drone and missile launchers. Iran’s ballistic missile storage has been centralized, making it easier to target. But its drone operations remain distributed and elusive. No one knows the true depth of Iran’s missile and drone inventories. But Iran reserves may prove deeper than expected if Moscow reciprocates past drone transfers with Russian-built variants now in mass production.

These challenges may appear discrete in the near term, particularly if Operation Epic Fury ends soon. But weighed against finite U.S. munitions inventories and limited replenishment capacity, every round expended carries a near-term opportunity cost measured in Pacific readiness.

There are reasons for cautious optimism. Simpler, cheaper weapons that can be fielded more quickly—like the LUCAS drone, which made its operational debut in this campaign—offer a path toward closing some of these gaps. Beyond ground and maritime strike, the United States urgently needs to scale affordable air defense interceptors purpose-built for the drone threat. To this end, Ukraine’s experience with low-cost counter-drone systems may offer a useful model. But promising concepts are not production lines. Prototypes must still be developed, refined, and scaled into mass production—a process that demands both investment and time.

Given the size of the U.S. military relative to its commitments, every operation—even a short one—imposes opportunity costs. To deter China, much less defeat it, the United States will need orders of magnitude more munitions and ready forces than it possessed even prior to Epic Fury. This reality should weigh heavily on how this campaign is carried into the future.

Stacie Pettyjohn is a senior fellow and director of the CNAS Defense Program. Philip Sheers is an associate fellow with the CNAS Defense Program.

To interview either author, please reach out to Charles Horn at [email protected]

For more on munitions investment trends, see Stacie Pettyjohn and Hannah Dennis, Precision and Posture and Production Is Deterrence. On defense industrial base constraints, see Becca Wasser and Philip Sheers, Production Lines to Front Lines. On counter-drone challenges, see Stacie Pettyjohn and Molly Campbell, Countering the Swarm. For a historical comparison of air campaigns, see Becca Wasser et al., The Air War Against the Islamic State. For the potential tanker constraints see Michael Marrow, “How Tanking, Airlift Could Be Constrained by Iran Ops.”