Iran War Drains U.S. Missile Arsenal, Raising Fears Over Future China Showdown

The United States has enough missiles to sustain its current military campaign against Iran under the present ceasefire conditions, but the far bigger strategic risk lies in the next war — particularly a potential conflict with China — as stockpiles of several critical precision munitions have been sharply depleted and will take years to rebuild, according to a report by the Center for Strategic and International Studies (CSIS), published on April 24th, 2026.

The CSIS report in question, ‘Last Rounds? Status of Key Munitions at the Iran War Ceasefire,’ found that in the 39 days of fighting before the ceasefire in Operation Epic Fury, U.S. forces heavily relied on seven key missile systems: Tomahawk land attack missiles, Joint Air-to-Surface Standoff Missiles (JASSM), Precision Strike Missiles (PrSM), Standard Missile-3 (SM-3), Standard Missile-6 (SM-6), Terminal High Altitude Area Defense (THAAD) interceptors, and Patriot PAC-3 interceptors. For four of those systems, the United States may have expended more than half of its prewar inventory.

CSIS estimated that the U.S. entered the war with roughly 3,100 Tomahawk missiles, 4,400 JASSMs, 90 PrSMs, 410 SM-3 interceptors, 1,160 SM-6 missiles, 360 THAAD interceptors, and 2,330 Patriot interceptors. Estimated wartime use reached more than 1,000 Tomahawks, more than 1,100 JASSMs, 40 to 70 PrSMs, 130 to 250 SM-3s, 190 to 370 SM-6s, 190 to 290 THAAD interceptors, and 1,060 to 1,430 Patriot interceptors.

Unit costs ranged from $1.6 million for PrSM to $28.7 million for each SM-3 interceptor, underscoring the financial scale of replenishment.

The report said the immediate battlefield problem is manageable because U.S. forces shifted away from high-end long-range missiles after suppressing much of Iran’s air defenses. Less expensive and more abundant alternatives, such as Joint Direct Attack Munitions (JDAMs), Small Diameter Bombs, and Joint Air-to-Ground Missiles, increasingly replaced premium munitions for ground strikes.

Meanwhile, Iranian missile and drone launches fell sharply after the opening days of the war. Iran fired more than 2,000 drones and 500 ballistic missiles in the first four days, but after one week, launches were down 83% and 90%, respectively.

Still, the long-term problem is severe. “Prewar inventories were already insufficient” for a peer conflict, particularly in the Western Pacific, the report said, warning that today’s lower stockpiles would constrain U.S. operations if another major conflict emerged. Rebuilding to prewar levels alone could take between one and four years, while building inventories to levels considered adequate for a potential war with China would take even longer.

Tomahawk missiles, long a centerpiece of U.S. naval strike operations, were among the most heavily used. The Washington Post reported more than 850 were fired in the first month, while later reporting by the Wall Street Journal put total expenditure above 1,000. CSIS said that could account for nearly all available Tomahawks in theater, particularly because ships cannot reload vertical launch systems at sea and must return to port.

RTX has since announced plans to raise annual Tomahawk production to more than 1,000 missiles under a framework agreement with the Trump administration. Japan, however, has reportedly been warned that deliveries of its planned 400 Tomahawks may be delayed because of the war.

JASSM-ER missiles, the stealthy long-range air-launched cruise missiles used heavily by B-52 bombers, also saw major depletion. Bloomberg reported more than 1,000 were fired in the first month of the war, and CSIS estimated about 1,100 had been used by the ceasefire.

Unlike Patriot or THAAD, international competition for new JASSM production is somewhat lower because operators such as Poland, Australia, and Finland have not recently drawn down their own stocks. Still, the U.S. inventory took a major hit, especially given the importance of these weapons in any future Pacific contingency.

The Precision Strike Missile, the Army’s successor to ATACMS, was even more constrained. Only about 90 were estimated to be in inventory before the war because deliveries began only in 2023. U.S. use was estimated at 40 to 70 missiles, and one Army official reportedly said the “entire inventory” had been expended, though other officials said some remain.

Lockheed Martin had already targeted annual production of 400 units and later announced further expansion under the Trump administration’s wartime production framework. Some older ATACMS, potentially as many as 800, remain available as a stopgap.

On the missile defense side, shortages are even more strategically sensitive because there are few substitutes. SM-3 interceptors, used primarily against ballistic missiles, are among the most expensive systems at $28.7 million each. The U.S. inventory was estimated at 410 before the war, with 130 to 250 potentially used during the conflict.

These came on top of earlier expenditures against Iranian attacks in 2024 and the 2025 Twelve-Day War, when around 80 more were fired. The latest Block IIA variant has particularly slow replenishment because of its long manufacturing timeline.

SM-6 interceptors, used mainly against aircraft and cruise missiles but also capable against ballistic missiles, were estimated at 1,160 prewar, with wartime use of 190 to 370. RTX plans to lift SM-6 production to more than 500 missiles annually, but near-term deliveries remain limited by industrial capacity and multi-year procurement cycles.

THAAD interceptors were identified as the single most critical munition due to their low inventory, high use and lack of alternatives. CSIS estimated only 360 interceptors existed before the war, with 190 to 290 expended. No new THAAD interceptors have been delivered since August 2023, and deliveries are not expected to resume until April 2027.

Lockheed Martin plans to raise annual THAAD production capacity to 400 from just 96 currently. The report also flagged vulnerability in THAAD’s AN/TPY-2 radars, noting only 13 have been delivered to the United States so far, and replacement would take significant time if multiple systems were lost.

Patriot interceptors face perhaps the greatest allied competition. The U.S. inventory was estimated at 2,330 before the war, with 1,060 to 1,430 used during operations. Eighteen other countries use the Patriot system, and roughly half of the annual production already goes to foreign partners.

Ukraine has received more than 600 Patriot interceptors from the United States and allies, while countries such as Switzerland have warned they may seek alternatives if deliveries are delayed. Lockheed Martin plans to raise annual PAC-3 MSE production to 2,000 by 2030 from about 600 now, but that expansion remains years away.

The Pentagon’s fiscal year 2027 budget request reflects that urgency. CSIS said the administration requested large procurement quantities across all seven systems to restore inventories and move the missile industrial base onto a “wartime footing.”

However, the report also stressed that even if Congress approves the funding, near-term deliveries will remain low because procurement decisions made years ago determine what reaches the field now. Small orders in prior years continue to constrain supply.

The report found that replenishing depleted missile inventories will take far longer than many policymakers assume, with total delivery timelines ranging from 42 months for Patriot PAC-3 MSE interceptors to as much as 64 months for SM-3 Block IIA missiles. Tomahawks require about 47 months from appropriation to full delivery, JASSM around 48 months, PrSM 46 months, while both SM-6 and THAAD take roughly 53 months.

Historically, manufacturers could make first deliveries within about 24 months, but surging demand and limited industrial capacity have pushed lead times to 36 months or more, meaning some systems may take over four years to fully replace.

Over the past five years, the U.S. defense industry has produced these missiles at a pace far below what was consumed during the Iran conflict, highlighting how difficult replenishment will be. On average, each year, manufacturers delivered about 79 Tomahawk missiles, 385 JASSMs, 56 Precision Strike Missiles (PrSM), 40 SM-3 Block IB interceptors, just 13 SM-3 Block IIA interceptors, 96 SM-6 missiles, 28 THAAD interceptors, and 183 Patriot PAC-3 MSE interceptors.

Even with recent plans to expand production, replacing wartime expenditure will take several years, particularly as U.S. allies are also drawing from the same production lines. So, the CSIS argues that the answer is not simply buying more premium missiles but also fielding cheaper complementary systems.

The report pointed to the Low-Cost Uncrewed Combat Attack System (LUCAS), modeled on Iran’s Shahed-136 drone, which costs about $35,000 and can strike targets roughly 500 miles away, albeit with only a 40-pound warhead.

It also highlighted low-cost drone defense systems such as APKWS rockets, Anduril’s Roadrunner, Raytheon’s Coyote, and C-RAM guns, arguing the United States cannot afford to routinely use $1 million or $4 million interceptors against low-cost drones.

The broader conclusion, however, was strategic rather than industrial. President Donald Trump’s administration, the report said, appears to have accepted the tradeoff of burning through munitions now to decisively win the current conflict rather than preserving stockpiles for a future war that may or may not come.

Once Operation Epic Fury concludes, the U.S. can shift its focus back to the Indo-Pacific, and missile stockpiles can gradually begin to recover. However, rebuilding depleted inventories will be a slow process, and restoring them to prewar levels, let alone expanding them to the scale needed for a potential conflict with China, is likely to take several years.

Tanmay Kadam is a geopolitical observer based in India. He has experience working as a Defense and International Affairs journalist for EurAsian Times. He can be contacted at tanmaykadam700@gmail.com.