Iran conflict depletes U.S. interceptors, raising South Korea air-defense concerns

Lockheed Martin plans to lift Patriot output to 2,000 a year

The United States is working with defense contractors to rebuild the depleted interceptor stocks, but officials and analysts say replacing the missiles will take time. Lockheed Martin, which produces the Patriot PAC-3 Missile Segment Enhancement interceptor, delivered a record 620 missiles in 2025. Under a seven-year agreement with the U.S. government, the company plans to increase annual production capacity from about 600 interceptors to as many as 2,000. The U.S. government has also reached agreements aimed at dramatically increasing production capacity for components used in both Patriot and THAAD interceptors.

Expanding production requires new manufacturing capacity, additional suppliers and larger supplies of specialized components, and even with accelerated production, rebuilding inventories sufficient for several simultaneous military contingencies could take years. The Pentagon has increasingly pressed defense manufacturers to shorten production timelines as the Iran war continues to consume precision weapons and air-defense interceptors.

The urgency reflects the extraordinary rate at which advanced weapons have been consumed during the conflict. Analysts estimate that U.S. forces fired hundreds of Tomahawk cruise missiles and more than 1,000 Patriot and THAAD interceptors during the early phase of the war, along with large numbers of tactical ballistic missiles. Recent reporting indicates that roughly 65% of the U.S. Patriot inventory and 38% of its THAAD inventory may have been expended since fighting with Iran began.

The Center for Strategic and International Studies estimated in late July that the United States had fewer than 1,000 Patriot interceptors remaining and about 250 interceptors for the Terminal High Altitude Area Defense system. Other estimates based on prewar inventories and reported expenditures place the remaining Patriot stockpile at fewer than 827 interceptors and the THAAD inventory at fewer than 278. Exact U.S. military stockpile figures are classified, and the estimates have not been confirmed by the Pentagon.

The growing demand for interceptors in the Middle East has also affected U.S. forces stationed in Northeast Asia. Gen. Xavier Brunson, commander of U.S. Forces Korea, told the Senate Armed Services Committee in April that THAAD interceptors were being moved from South Korea to the Middle East, although the THAAD system itself was expected to remain on the Korean Peninsula. Earlier movements of Patriot equipment at Osan Air Base fueled concern in South Korea that some U.S. air-defense assets could be reassigned to the Middle East.

South Korean officials have said the alliance retains sufficient capabilities to deter North Korea, but the movements have renewed debate over whether a prolonged Middle East conflict could put greater pressure on air defenses in Northeast Asia. Patriot PAC-3 interceptors form part of the layered missile-defense network used by South Korean and U.S. forces against North Korea’s ballistic missile threat. The network also includes the higher-altitude THAAD system and South Korea’s domestically developed Cheongung-II interceptor. The PAC-3 is designed primarily to destroy ballistic missiles and other airborne threats during the terminal stage of flight using hit-to-kill technology. South Korea operates its own Patriot systems while U.S. Forces Korea also maintains Patriot defenses on the peninsula.

U.S. force movements have extended beyond missile-defense systems. More than 2,200 Marines assigned to the Japan-based 31st Marine Expeditionary Unit were ordered from the Indo-Pacific region to the Middle East as the Iran conflict intensified. The unit normally operates from Okinawa with amphibious ships based in Japan and provides a rapidly deployable combat force for contingencies across the Indo-Pacific. Its deployment has added to concern that a prolonged Middle East conflict could tie down forces that would otherwise be available for contingencies involving the Korean Peninsula or Taiwan.

A U.S. government official, speaking on condition of anonymity, said shifting surveillance and air-defense assets toward the Middle East could leave U.S. forces in South Korea more exposed in the event of a conflict with North Korea. The official also raised concern that doubts about U.S. conventional defense capabilities could intensify debate in South Korea and Japan over whether the countries need stronger independent deterrent capabilities.

The effects of shrinking interceptor inventories extend beyond the Korean Peninsula. Ukraine remains heavily dependent on Patriot systems to defend cities and critical infrastructure against Russian ballistic and cruise missile attacks. The strain on available interceptors has complicated Western efforts to maintain deliveries to Ukraine while simultaneously supplying U.S. forces and allies in the Middle East. Demand for Patriot interceptors has increased sharply worldwide as the wars in Ukraine and the Middle East have demonstrated their value against ballistic missiles. Nineteen countries now operate the Patriot system.

Defense analysts warn that prolonged shortages could have strategic consequences beyond the Middle East. China and Russia closely monitor U.S. weapons inventories and the industrial capacity needed to replenish them. If Washington is perceived as having insufficient stocks to sustain another major conflict, analysts say, that could weaken deterrence in Europe or the Indo-Pacific. The concern is particularly significant in Northeast Asia, where U.S. forces must simultaneously prepare for potential North Korean missile attacks and broader regional contingencies involving China. The longer the Iran conflict continues, analysts say, the more difficult it may become for the United States to balance those commitments while rebuilding the missile inventories needed to support them.