Is Iran holding back on its prized missiles to 'exhaust' US and Gulf air defences?

Recent Iranian missile and drone barrages across the Gulf and towards Israeli territory have been intercepted at high rates, underlining the sophistication of regional air defence systems and their operators.

The question is no longer whether they can down incoming threats from Iran, as they have proven, but whether they can sustain repeated waves of fire over a protracted period of time, particularly as Tehran has an expansive arsenal with many prized missiles still not used.

The arithmetic of air defence

Missile defence systems such as Patriot, THAAD, Arrow and SM-series interceptors are technologically advanced and combat-proven, but they are also expensive and finite.

Intercepting a ballistic missile can cost millions of dollars per shot, and in some scenarios, multiple interceptors are fired at a single incoming threat to ensure a kill. By contrast, many of the drones used in recent Iranian strikes are significantly cheaper and easier to produce at scale, and often harder to intercept than ballistic missiles.

"Missile interceptors are a big concern… We are using these interceptors faster than we can make them," Kelly Grieco, a senior fellow at the Stimson Centre told Bloomberg, highlighting the strain that high-tempo engagements can impose on stockpiles.

William Alberque, senior adjunct fellow at the Pacific Forum, also told Bloomberg that "magazine capacity was already low for the US and its partner nations", suggesting that inventories were not built for prolonged saturation exchanges.

The issue is not immediate defensive failure. Interception rates in recent exchanges have remained high, but the concern is sustainability - how long those rates can be maintained if launch volumes remain elevated.

Iran’s volume advantage

Iran’s strength lies less in precision than in scale, fielding one of the largest ballistic missile arsenals in the Middle East, including short- and medium-range systems capable of reaching Gulf capitals, US bases and Israeli territory. It also deploys cruise missiles and has mass-produced loitering munitions, including Shahed-type drones, that have featured prominently in recent operations.

While Iran has unveiled what it describes as hypersonic missiles, such as the Fattah series, claiming high speeds and manoeuvrability designed to challenge missile defences, their use has been limited.

Independent analysts remain cautious about the full operational capabilities of these systems, and they have not dominated the current strike profile.

Daniel Shapiro, a former senior Pentagon official, told Reuters that sheer volume alters the defensive equation.

"Iran has many more ballistic missiles that can reach US bases than the US has interceptors… some Iranian weapons will get through," he said, underscoring the mathematical imbalance that can emerge over time.

The pattern so far suggests a reliance on high-volume, relatively lower-cost systems rather than the systematic use of the most advanced missiles apparently in Iran’s inventory.

Is Tehran holding back?

That pattern has prompted a further question: whether Iran is deliberately pacing its escalation for some long-term goal.

While Tehran has showcased more advanced missile technologies in recent years, including solid-fuel medium-range systems and claimed hypersonic weapons, these have not featured prominently in the largest recent barrages.

Instead, the emphasis has been on drones and conventional ballistic missiles deployed in waves, which has been described as an attritional logic.

"Attrition strategy makes operational sense from Iran’s perspective… they are calculating the defenders will exhaust their interceptor missiles and the political will of Gulf states will crack," Grieco told Bloomberg.

There is no public confirmation that Iran is deliberately reserving higher-end systems, but the current campaign appears calibrated to impose cost rather than to showcase peak technological capability.

If more advanced missiles are being conserved, the cost asymmetry could sharpen further in a prolonged exchange.

What the Gulf, US and Israel deploy

Against this stands a layered defensive architecture.

Gulf states rely heavily on Patriot and THAAD batteries to defend key infrastructure and urban centres, and the US supplements this with regional deployments and naval assets equipped with Aegis combat systems and SM-series interceptors.

Israel fields a dense, multi-layered shield comprising Iron Dome for short-range threats, David’s Sling for medium-range missiles, and Arrow systems for ballistic threats.

These systems have demonstrated high interception rates, but each has practical limits. Naval vessels carry a finite number of vertical launch system cells and must return to port to reload. Land-based batteries require resupply from production lines that are neither instantaneous nor unlimited, and interceptors cannot be manufactured overnight.

The United States retains deeper stockpiles and industrial capacity than any regional actor, yet sustained, multi-theatre commitments can place pressure even on larger inventories.

Qatar and the UAE have also denied reports that they are running short on air defence interceptors, and insist they have enough weapons to block the Iranian assault on Gulf cities, but even the US is also looking at increasing supplies as its stockpiles are depleted.

When does strain become risk?

In a short, intense exchange lasting days, defenders retain the advantage, but in a sustained campaign measured in weeks, the equation becomes more complex.

Localised depletion, rather than total exhaustion, becomes the more plausible risk, and as burn rates rise, the probability of "leakage" increases, meaning a higher likelihood that some missiles or drones penetrate defences.

That does not imply imminent collapse, but it does shift the contest from technological capability to industrial endurance and political resolve.

Ultimately, the battle may hinge less on who intercepts more missiles on a single night than on which side can sustain the tempo longer.