Interceptor Crisis: Israel Days From Running Out of Arrow-3 as US THAAD Stocks Drain in Iran War, RUSI Warns ‘Years Needed to Rebuild

(DEFENCE SECURITY ASIA) — The rapidly intensifying missile defence campaign of the United States–Israel coalition against Iran is entering a potentially decisive logistical phase as interceptor inventories begin approaching critical depletion thresholds after only weeks of sustained high-tempo combat operations.

A detailed assessment released by the Royal United Services Institute indicates that Israel’s Arrow ballistic-missile interceptors could be fully exhausted within days, while the United States faces a comparable strain on its THAAD interceptor inventory if the current operational tempo continues.

The analysis, combined with emerging diplomatic signals from Washington regarding a possible negotiated settlement to the Iran conflict, suggests that industrial endurance and munitions production capacity may now be shaping strategic decision-making as much as battlefield developments.

RUSI Report Highlights Rapid Depletion of High-End Interceptors

The Royal United Services Institute assessment titled “Over 11,000 Munitions in 16 Days of the Iran War: ‘Command of the Reload’ Governs Endurance” frames the conflict not only as an operational contest but also as a test of the coalition’s ability to sustain high-technology interceptor inventories.

According to the report, Israel’s Arrow interceptor missile inventory is now approaching critical depletion after sustaining heavy firing rates against Iranian ballistic missiles and drone salvos during the early phases of the conflict.

The think tank estimates that at the current operational tempo, Israel could completely expend its Arrow interceptor stockpile by the end of March, placing the country only days away from running out of its primary exo-atmospheric missile defence capability.

This conclusion reflects the high burn rate of interceptors required to counter Iranian attacks that have averaged 33 ballistic missiles and approximately 94 drones daily following the conflict’s initial escalation phase.

The study further notes that the operational strain has been compounded by the damage or degradation of radar systems, forcing air defence units to expend more interceptors per incoming threat in order to maintain acceptable interception probabilities.

This dynamic has significantly increased interceptor consumption rates, intensifying the pressure on Israel’s already limited stockpile of Arrow missiles designed to counter medium-range ballistic missile threats.

While Israeli officials have publicly rejected claims that the country faces an immediate interceptor shortage, the RUSI analysis suggests that the pace of expenditure may be approaching a structural limit.

The report therefore frames Israel’s missile defence posture as increasingly dependent on rapid resupply, industrial replenishment, or operational adaptation should Iranian attack patterns intensify again.

READ: Interceptor Stocks ‘Dangerously Low’: US, Israel and Gulf States Face Strategic Breaking Point as Iran Intensifies Missile Barrage

US THAAD Interceptors Also Under Sustained Operational Pressure

The RUSI assessment also highlights growing pressure on the United States’ Terminal High Altitude Area Defense (THAAD) interceptor inventory, which has been heavily employed in the coalition’s layered missile defence architecture during the Iran war.

According to the report, the United States could be approximately one month or less away from exhausting available THAAD interceptor stocks if current expenditure rates continue without significant operational adjustment.

Although exact stockpile figures remain classified, the report notes that the rapid pace of interceptor use during the conflict reflects a broader phenomenon described as the “magazine abyss,” where high-end precision munitions are depleted faster than they can be replenished.

During the first 16 days of the conflict, coalition forces are estimated to have expended approximately 11,294 munitions, representing a combined cost of roughly US$26 billion (RM98.8 billion).

This scale of expenditure highlights the economic and industrial dimensions of modern high-intensity warfare, where the sustainability of advanced weapons systems becomes a central determinant of operational endurance.

The report also emphasizes that complex interceptor systems such as THAAD cannot be rapidly replaced due to supply-chain constraints, rare materials requirements, and limited production capacity within the defence industrial base.

As a result, replenishing the interceptors expended during the initial weeks of combat could require years of production recovery, creating strategic vulnerabilities if similar high-intensity conflicts occur elsewhere.

This dynamic has significant implications for the broader US global force posture, particularly given the simultaneous missile defence commitments associated with other potential theatres such as Ukraine and Taiwan.

Replenishment Timelines Reveal Multi-Year Interceptor Gap as Arrow-3 and THAAD Stocks Enter “Magazine Abyss”

The Royal United Services Institute assessment indicates that replenishment timelines for high-end interceptors such as Israel’s Arrow-3 and the United States’ THAAD are measured in years rather than months because production depends on complex manufacturing chains, rare materials, and limited industrial capacity.

The report links the current burn rate during the Iran war to what analysts describe as a “magazine abyss,” where even partial depletion of advanced interceptors cannot be reversed quickly enough to sustain prolonged high-intensity missile defence operations.

RUSI estimates that Israel’s Arrow interceptor inventory is now approaching complete exhaustion by the end of March, reflecting sustained firing rates since the conflict began in late February and highlighting the structural limits of the current production cycle.

Earlier analytical modelling cited in the report notes that during the first ninety-six hours of heavy combat, Israel’s Arrow inventory was reduced by more than half, a level of expenditure that would require more than thirty months to replace at pre-war production rates.

The same modelling suggests that if the initial burn rate had continued without adjustment, available Arrow interceptors would have been depleted within approximately eight additional days, illustrating how quickly modern missile defence inventories can collapse under sustained ballistic-missile pressure.

Production realities further complicate recovery timelines because each Arrow-3 interceptor requires months of manufacturing work involving precision propulsion systems, guidance electronics, and specialized materials supplied through long-lead industrial contracts placed years in advance.

Israel Aerospace Industries remains the primary producer of the Arrow system, with certain components manufactured in cooperation with the United States, meaning that expansion of output requires coordinated adjustments across multiple industrial facilities rather than a single production line.

Even after signing multi-billion-shekel agreements to expand Arrow-3 production and approving emergency procurement funding, existing production lines were already operating near full capacity before the war, limiting the speed at which additional interceptors can be delivered.

Export obligations for Arrow-3 interceptors, including large international contracts scheduled for delivery later in the decade, further constrain manufacturing flexibility because the same factories, materials, and workforce must support both domestic requirements and previously committed foreign orders.

The report concludes that under current conditions, replacing the interceptors expended during the present conflict could take two to three years even with accelerated production, reinforcing the broader strategic warning that modern high-intensity missile warfare is increasingly determined by industrial endurance rather than battlefield performance alone.

“Command of the Reload” Emerges as Decisive Strategic Factor

RUSI frames the conflict through the concept of “Command of the Reload,” arguing that modern warfare increasingly hinges on the ability of states to sustain high-technology weapons inventories rather than simply achieving initial battlefield success.

The report suggests that the Iran conflict demonstrates how industrial capacity and logistics resilience can determine strategic endurance in prolonged missile and air defence campaigns.

Under this framework, the ability to replenish interceptor inventories quickly enough becomes a decisive strategic variable shaping operational freedom and defensive resilience.

Without sufficient replenishment capacity, even technologically superior missile defence systems risk gradual degradation as stockpiles decline faster than production lines can restore them.

The analysis warns that the coalition could eventually face an operational environment in which greater numbers of missiles and drones penetrate air defence systems, creating the risk of increased infrastructure damage.

Such “leakers,” as missile defence planners describe them, represent a key operational concern if interceptor inventories fall below sustainable levels.

While the war could technically continue using alternative defensive measures or lower-tier interceptors, the report suggests that doing so would likely involve accepting higher levels of risk to critical infrastructure and civilian areas.

This industrial sustainability problem therefore transforms the war from a purely military contest into a strategic endurance competition between missile production capacity and defensive intercept capability.

Independent Reports Reinforce Concerns Over Interceptor Shortages

Multiple independent reports released in mid-March have echoed concerns about interceptor depletion within the US-Israel coalition’s missile defence network.

Officials speaking to media outlets indicated that Israel had already entered the current conflict with reduced interceptor inventories following earlier fighting in the previous summer, compounding the logistical strain of the current campaign.

According to those reports, Israeli officials informed Washington that the country was running critically low on ballistic missile interceptors as Iranian missile and drone attacks continued during the early weeks of the war.

The situation has reportedly been exacerbated by Iran’s use of cluster munitions in ballistic missile warheads, which increases the complexity of interception and can require multiple interceptors to neutralize each threat.

Despite these reports, Israeli authorities have publicly denied that the country faces any urgent missile defence shortage.

Officials have stated that Israel prepared for prolonged combat operations and is already developing solutions to address the evolving operational environment.

At the same time, reports indicate that the Israeli government has approved emergency defence procurement funding, suggesting that the issue of interceptor availability is receiving high-level attention within the national security establishment.

These developments highlight the tension between public messaging designed to maintain deterrence credibility and internal concerns about sustaining missile defence operations over extended periods.

Interceptor Shortages May Influence Diplomatic Momentum

The RUSI analysis also links the interceptor depletion issue to recent diplomatic developments surrounding the Iran conflict.

According to the report, the precarious state of interceptor inventories could help explain why US political leadership has begun signalling openness to winding down the war through diplomatic channels.

The think tank suggests that the industrial timeline required to replenish expended interceptors may create incentives for policymakers to pursue conflict termination before missile defence stockpiles reach critically low levels.

Recent statements from US leadership indicate that diplomatic discussions with Iran are underway as part of a broader effort to explore potential pathways toward ending the conflict.

Public remarks have described these negotiations as “very good and productive,” while suggesting that Iran may be open to reaching a negotiated settlement.

The United States has also reportedly postponed additional strikes against certain targets in order to provide diplomatic space for negotiations to proceed.

However, Iranian officials have offered mixed responses regarding the status of negotiations, with some statements suggesting that reports of direct talks may be overstated.

These contrasting narratives illustrate the complexity of interpreting diplomatic signals during an ongoing conflict where military operations, strategic messaging, and negotiation dynamics interact simultaneously.

Strategic Uncertainty Remains as War Continues

Despite the growing attention to interceptor depletion, the operational trajectory of the Iran conflict remains fluid.

Iranian missile and drone attacks have reportedly decreased compared with the earliest stages of the war, although the threat environment remains active and unpredictable.

Variations in daily missile salvo sizes can significantly alter interceptor consumption rates, making it difficult to predict precisely how long existing stockpiles will last.

Additionally, both the United States and Israel have emphasized their ability to adapt operational strategies, including shifting defensive responsibilities among different systems or accelerating production lines where possible.

Defence analysts therefore caution that precise figures regarding interceptor depletion remain uncertain due to the classified nature of stockpile data.

The RUSI estimates and other external analyses should therefore be interpreted as informed assessments rather than definitive measurements of current inventory levels.

Nevertheless, the emerging debate over interceptor sustainability underscores the broader challenge facing modern militaries engaged in high-intensity missile warfare.

In conflicts defined by large-scale missile salvos, advanced air defence networks, and expensive interceptor technologies, the decisive factor may ultimately be the side capable of sustaining production and resupply faster than its adversaries can launch attacks.