U.S. military stockpiles of advanced defensive missiles have been significantly depleted during the ongoing conflict with Iran, raising concerns about the country’s capacity to deter future missile threats from other global adversaries. According to an independent analysis by the Center for Strategic and International Studies (CSIS), nearly 60% of the United States’ Patriot and THAAD interceptors, which protect American forces against missile attacks, were used between February 28 and July amid escalating conflict in the region.

The inventory of these sophisticated interceptors fell from nearly 2,800 at the start of the war to about 1,100 by late July, with Patriots accounting for nearly two-thirds of the depletion and THAAD missiles experiencing a 40% reduction. CSIS director Tom Karako described the loss as a “generational annihilation” of U.S. theater missile defense capability. Although the Pentagon and White House have declined to confirm the precise figures, they maintain that the U.S. possesses ample munitions stockpiles overall.

President Donald Trump has acknowledged the situation, noting that while some munitions are available in virtually unlimited supply, others are in tighter availability. U.S. commanders have reportedly been conserving Patriot and THAAD interceptors in operational theaters. During much of August, for example, U.S. forces refrained from deploying high-end missiles in response to Iranian attacks on oil tankers in the Strait of Hormuz. However, reports suggest that Patriots were employed recently to counter Iranian rocket attacks on U.S. bases in Jordan, although U.S. officials have neither confirmed nor denied this.

The reduced inventory has prompted concerns among defense analysts and officials regarding the United States’ ability to deter potential aggression by China or Russia. The Council on Foreign Relations has warned that current stock levels may be insufficient to defend Taiwan in the event of a Chinese attack. Similarly, defense experts warn of vulnerabilities in European theaters if Russia initiates hostilities in the Baltic region. A U.S. defense official described the shortfall in Europe as “beyond critical,” emphasizing the risk to NATO allies.

Former Defense Secretary Leon Panetta emphasized the strategic importance of maintaining a credible deterrent, suggesting that the current depletion undermines U.S. military credibility. Karako also highlighted that knowledge of diminished missile stocks might embolden adversaries, potentially increasing the risk of conflict escalation.

Efforts to rebuild inventories began before the onset of hostilities, with directives from Trump and Defense Secretary Pete Hegseth to increase missile production. However, current manufacturing rates—approximately 620 Patriots and 96 THAAD missiles annually—fall well short of the quantities expended in the conflict’s early months. CSIS projects it will take at least three years to restore Patriot inventories and four years to replenish THAAD stocks, with experts agreeing that even larger stockpiles will be necessary to deter great-power conflicts.

The missile shortage predates the current conflict, reflecting longstanding challenges in balancing defense procurement with emerging threats. Experts attribute the situation to shifts in military technology, where cheaper, more accessible missile and drone systems are widely available, complicating traditional U.S. defense paradigms focused on a limited number of adversaries. This evolving threat environment has outpaced the Pentagon’s acquisition and production planning.

In response, the Department of Defense has begun investing in lower-cost missile and drone defense systems, including deploying several anti-drone interceptors. Despite a $7.7 billion budget allocation for such programs in last year’s defense bill, a significant portion of these funds—over 90%—remained unspent after 13 months, according to observers.

Moving forward, the U.S. faces the dual challenge of accelerating production of advanced interceptors while developing cost-effective alternatives to address the shifting missile threat landscape during the interim period.