29MAR

Arrow-3 81% gone; full depletion looming

2 min read

09:10UTC

RUSI projected Arrow-3 stocks fully exhausted by end of March, with $26 billion spent on 11,294 munitions in the first 16 days alone.

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ConflictDeveloping

Key takeaway

Israel may have entered April without its primary ballistic missile defence shield.

The Royal United Services Institute projected that Israel's Arrow-3 interceptor stocks were 81.33% depleted by 26 March and would be fully exhausted by the end of the month. ¹ In practical terms, fewer than one in five of Israel's pre-war upper-tier interceptors remained five days ago. The US THAAD system faces similar pressure, with stocks potentially exhausted within one month at current expenditure rates.

The cost figures behind the depletion expose a structural asymmetry. The US-Israel coalition fired 11,294 munitions in the first 16 days at an estimated cost of $26 billion. At that rate, the unfunded $200 billion supplemental request covers roughly four months of operations. The interception rate held at 92%, but Iran's missiles cost a fraction of the interceptors that destroy them. By RUSI's estimate, Iran spends roughly $1 for every $10 the coalition spends to counter it.

Replenishment takes years, not months. Arrow-3 production depends on complex supply chains and specialist components. Iran's deployment of a cluster warhead on the same day may reflect awareness that the defence gap is imminent. If RUSI's projection held, Israel entered April with no upper-tier missile defence. The next cluster warhead arrives into open sky.

Deep Analysis

In plain English

Israel's main defence against long-range Iranian missiles is called Arrow-3. Think of it as a very expensive interception system that shoots down incoming missiles before they land. Each interceptor missile costs several million pounds. RUSI, a respected British defence think tank, estimated that by 26 March, roughly four in five of Israel's pre-war supply had been used up. The projection was that the last ones would be fired by end of March. Replacing them takes years, not weeks. Iran's missiles cost far less to build than the interceptors that destroy them. Iran fired 1 for every £10 spent defending against it. If the shield is empty, Iranian missiles arrive undefended.

What could happen next?

Risk
If Arrow-3 stocks are genuinely exhausted, Iran's ballistic missiles arrive uncontested at Israeli cities, and THAAD becomes the sole remaining upper-tier defence with its own stocks draining.
Immediate · 0.75
Consequence
The cost-exchange ratio forces a strategic choice: continue operations at $800 million per day with no replenishment path, or negotiate before the THAAD gap similarly opens.
Short term · 0.8
Consequence
Arrow-3 depletion removes the deterrent value of the interception system; Iran's operational calculus on strike tempo changes immediately.
Immediate · 0.8

Source Landscape

This story draws on neutral-leaning sources

Primary parallel: The 1973 Yom Kippur War's most dangerous phase came when Israeli ammunition stocks approached exhaustion on Day 8. The US emergency airlift on Day 9 changed the strategic balance within 24 hours. Arrow-3 production timelines of years, not days, mean no equivalent airlift solution exists for this depletion.

Counter-parallel: NATO's ammunition depletion during the 1999 Kosovo campaign produced diplomatic pressure for a quick settlement rather than tactical collapse. The difference is Kosovo involved no direct threat to coalition cities; Israel faces ballistic missiles targeting population centres.

At $800 million per day in US spending, interceptor replenishment is the single largest line item in the unfunded supplemental. Arrow-3 missiles cost approximately $3.5 million each; THAAD interceptors cost approximately $10 million each. At the 11,294-munitions-in-16-days expenditure rate, the $200 billion supplemental covers roughly four months of operations before further funding is required.

Replenishment production cannot be accelerated to wartime pace in weeks. Elbit Systems and Boeing, the primary Arrow-3 manufacturers, operate on multi-year production contracts. The gap between exhaustion and replenishment is measured in years, not the months that a Congressional vote might eventually authorise.

Consensus view: RUSI's Justin Bronk and the International Institute for Strategic Studies both assess the cost-exchange ratio as strategically unsustainable. At $1 Iranian launch cost for every $10 in coalition interception cost, Arrow-3 exhaustion was predictable from Day 1 of high-tempo operations.

Counter-view: Israeli Defence Ministry sources cited by Haaretz suggest the 81.33% depletion figure conflates different Arrow variants and does not account for transferred US stocks. RUSI's single-source estimate may overstate the severity of the gap.

Key tension: Whether Israel entered April genuinely without upper-tier missile defence, or whether undisclosed US transfers have bridged the gap before the cluster warhead threat fully materialises.

Sources:Defence Security Asia (citing RUSI)

Mentions:Arrow-3 →THAAD →RUSI →

First Reported In

Update #53 · Trump drops Hormuz goal; toll becomes law

Defence Security Asia (citing RUSI)· 31 Mar 2026

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Causes and effects

Caused by

One ship through Hormuz in 24 hours

High missile interception rates across March drove the Arrow-3 depletion trajectory that RUSI projected would reach exhaustion by end of March.

Occurred 29 Mar 2026

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This Event

Arrow-3 81% gone; full depletion looming

If the projection held, Israel entered April without upper-tier ballistic missile defence for the first time since the system became operational.

Different Perspectives

South Korean financial markets

South Korea, which imports virtually all its crude oil, is absorbing the war's economic transmission most acutely among non-belligerents. The second KOSPI circuit breaker in four sessions — with Samsung down over 10% and SK Hynix down 12.3% — reflects an industrial economy unable to reprice energy costs that have risen 72% in ten days. The market response indicates Korean industry cannot sustain oil above $100 per barrel without margin compression across manufacturing, semiconductors, and shipping.

Migrant worker communities in the Gulf

The first confirmed civilian deaths in Saudi Arabia — one Indian and one Bangladeshi killed, twelve Bangladeshis wounded — fell on communities with no voice in the military decisions that placed them in harm's way. Migrant workers live near military installations because that housing is affordable, not by choice. Bangladesh and India face the dilemma of needing to protect nationals who cannot easily leave a war zone while depending on Gulf remittances that fund a substantial share of their domestic economies.

Azerbaijan — President Ilham Aliyev

Aliyev treats the Nakhchivan strikes as a direct act of war against Azerbaijani sovereignty, placing armed forces on full combat readiness and demanding an Iranian explanation. The response is calibrated to maximise international sympathy while stopping short of military retaliation — Baku cannot fight Iran alone and needs either Turkish or NATO backing to credibly deter further strikes.

Oil-importing nations (Japan, South Korea, India)

The Hormuz closure is an existential threat. Japan, South Korea, and India receive the majority of their crude through the strait — they will bear the heaviest economic cost of a war they had no part in.

Global South governments (Indonesia, Brazil, South Africa)

Neutrality was possible when the targets were military. 148 dead schoolgirls made it impossible — no government can explain that away to its own citizens.

Turkey

Has absorbed three Iranian ballistic missile interceptions since 4 March without invoking NATO Article 5 consultation. Each incident narrows Ankara's political room to continue absorbing without Alliance-level response.