WASHINGTON, — April 21, 2026 : Recent defense assessments indicate that the United States has expended a substantial portion of its key missile inventories during ongoing military operations against Iran, reducing the depth of high-end munitions available for other potential contingencies.
According to analyses derived from Pentagon-aligned data and independent research institutions, including the Payne Institute for Public Policy and the Center for Strategic and International Studies (CSIS), the United States has used significant quantities of both offensive and defensive missile systems in the opening phase of the campaign, identified in assessments as Operation Epic Fury.
Data indicates that at least 45 percent of the US inventory of Precision Strike Missiles (PrSM) has been expended. In parallel, defensive interceptor stocks have been drawn down heavily, with at least half of Terminal High Altitude Area Defense (THAAD) interceptors and nearly 50 percent of Patriot air defense interceptor missiles used during operations.
High Expenditure Rates in Initial Phase
Detailed assessments of the first 16 days of high-intensity operations show that US forces expended more than 6,000 munitions, including both strike weapons and air defense interceptors. During this period alone, approximately 198 THAAD interceptors were fired, representing around 40 percent of available US-operated THAAD systems at the time.
Patriot air defense systems, including PAC-3 interceptors, accounted for 402 missile launches in the same timeframe. These interceptors were used extensively to counter Iranian ballistic missile and drone attacks, often requiring multiple interceptors per incoming threat to ensure successful engagement.
Offensive missile usage also increased sharply. Combined expenditure of the Precision Strike Missile (PrSM) and the legacy Army Tactical Missile System (ATACMS) reached nearly 46 percent of available stock within the first 16 days. The PrSM, which is designed as a longer-range successor to ATACMS and launched from HIMARS platforms, saw its first operational combat use during these strikes.
Pre-Conflict Inventory and Production Constraints
Prior to the conflict, procurement levels for newer missile systems such as PrSM were relatively limited. Approximately 130 PrSM units were procured in fiscal year 2024, followed by about 250 units in fiscal year 2025, reflecting early-stage production levels.
THAAD interceptor inventories before the conflict were estimated between 534 and 632 units. Annual production capacity for THAAD has remained constrained, typically not exceeding around 100 interceptors per year, with some years recording no deliveries.
Patriot PAC-3 Missile Segment Enhanced interceptors have seen comparatively higher production rates, with recent annual procurement averaging close to 270 units. However, the scale of usage during the Iran operations has significantly reduced available stocks across all major air defense systems.
Sustainment of Current Operations and Strategic Implications
US defense officials have stated that existing inventories remain sufficient to sustain ongoing operations against Iran without immediate disruption. However, the reduction in high-end munitions has affected the broader strategic reserve required for other scenarios.
Pre-conflict war games and independent assessments had already projected rapid depletion of advanced munitions in a high-intensity conflict involving a near-peer adversary, particularly in the Indo-Pacific region. The current expenditure levels have further constrained these reserves.
Analysts note that, at the observed rate of usage, stockpiles of systems such as PrSM/ATACMS and THAAD could have been exhausted within approximately one month if sustained at similar intensity.
Industrial Base and Replenishment Timelines
Replenishment of depleted inventories is expected to take multiple years, driven by existing industrial capacity and production timelines. Estimates suggest that restoring THAAD interceptor levels alone could require between three and eight years under current production constraints.
Efforts are underway to expand manufacturing output. The US Department of Defense has initiated supplemental funding requests and entered into framework agreements with defense contractors, including Lockheed Martin, to increase production capacity. Plans include scaling up output of key systems such as PrSM and Patriot interceptors.
Despite these measures, analysts estimate that full restoration of missile inventories to pre-operation levels may take approximately three to five years, even with increased production rates.
Operational Adjustments and Global Stockpile Management
To sustain ongoing operations, the US military has drawn from global and theater-level stockpiles, including redeployments from other regions. These adjustments have affected availability of certain systems outside the Middle East.
The high tempo of operations has reflected sustained precision strike requirements combined with intensive air and missile defense activity. Thousands of targets have been engaged using precision-guided munitions, while defensive systems have been continuously employed to counter large-scale missile and drone attacks.
While current assessments indicate no immediate impact on the continuation of operations against Iran, defense planning continues to focus on rebuilding stockpiles and addressing longer-term readiness requirements for potential multi-theater contingencies, including scenarios involving near-peer adversaries such as China.
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