US Missile Shield Stockpiles Shrink After Iran Fighting, Analysis Warns

WASHINGTON-Recent fighting with Iran has further depleted US stockpiles of advanced air defence interceptors, raising concerns that American forces could face greater risks if hostilities resume and reducing flexibility for any future conflict elsewhere, according to a new analysis by the Center for Strategic and International Studies (CSIS).

The Washington-based think tank said inventories of Patriot and Terminal High Altitude Area Defense (THAAD) interceptors have fallen significantly since the conflict began, potentially forcing the United States and its regional allies to conserve high-end missile defences. The report said commanders could be compelled to accept greater operational risk by limiting interceptor use against incoming missiles and drones.

Mark Cancian, a retired Marine colonel and senior adviser at CSIS who co-authored the report with research associate Chris H. Park, said reduced inventories could slightly increase the likelihood of Iranian projectiles penetrating US defences. He said even a modest reduction in interceptor use could raise the chances of successful attacks.

The report comes as the five-month conflict continues to draw political scrutiny in the United States over military readiness, troop safety and the financial cost of operations. The war has also intensified debate over the availability of advanced precision-guided munitions and air defence systems.

Gen. Dan Caine, chairman of the Joint Chiefs of Staff, has advised President Donald Trump that the condition of US munitions stockpiles could influence future military operations involving Iran, according to a US official familiar with the discussions. The official, who spoke on condition of anonymity because of the sensitivity of the conversations, said the assessment formed part of Caine’s routine military advice to the president.

The Pentagon rejected suggestions that its operational capabilities have been significantly weakened. Pentagon chief spokesman Sean Parnell said in a statement that the US military remained fully capable of carrying out operations whenever directed by the president and continued to maintain a substantial arsenal to protect American personnel and national interests.

Although large-scale exchanges between Washington and Tehran have eased in recent days, Iran continues to demonstrate its ability to strike US positions. Iranian missiles and drones hit a base in Jordan on July 17, killing three American troops. A day later, another US service member died in Iraq during the controlled detonation of an Iranian drone, bringing the conflict’s reported US military death toll to 18.

Defence Secretary Pete Hegseth told lawmakers last week that the conflict has cost an estimated $37.5 billion. The Pentagon has requested $67 billion from Congress to replenish military inventories, including additional Patriot and THAAD interceptors and other advanced munitions consumed during the fighting.

The issue has also become a point of contention in Congress, where Democratic lawmakers have questioned the extensive use of finite missile inventories in a war launched by Trump alongside Israel on Feb. 28 without congressional approval.

Beyond the Middle East, defence analysts have warned that depleted stockpiles could reduce US readiness for other potential conflicts. CSIS said in May that replacing inventories of Patriot interceptors, THAAD interceptors and Tomahawk cruise missiles could require at least three years.

Using budget documents and other publicly available information, CSIS estimated that Patriot interceptor inventories declined from about 2,330 before the conflict to 1,030 when an April ceasefire took effect. Following the latest fighting, the think tank estimated remaining stocks at between 759 and 827 interceptors, representing a reduction of at least 65% from pre-war levels.

The report estimated that THAAD interceptor inventories fell from 452 before the conflict to between 232 and 262 by the start of the April ceasefire. Although some replenishment increased the inventory to between 234 and 278 interceptors, the total remains at least 38% below pre-conflict levels.

Cancian said lower inventories could influence operational doctrine by reducing the number of interceptors fired at each incoming threat. Rather than launching multiple interceptors against a single target, commanders may choose to fire fewer missiles to preserve stocks. He also said forces might allow missiles projected to land in unpopulated areas to pass without interception, accepting limited damage in order to conserve increasingly scarce air defence weapons.