How Long Can Iran’s Missile Arsenal and US THAAD Last in the 2026 Conflict?

Background

On 28 Feb 2026 a US‑Israel coalition launched “Epic Fury”. Iran responded with “Real Commitment 4”, conducting at least 13 attack rounds against US and Israeli sites across the Gulf region.

Model Overview

State Variables

U – usable THAAD interceptors on the US‑Israel side.

I – remaining Iranian ballistic missiles that can be launched.

V – number of operational Iranian missile launch vehicles.

Dynamic Equations

The launch rate R(t) of Iranian missiles is modeled as: R(t) = r0 * V(t) * I(t) / I0 where r0 is the nominal missiles‑per‑vehicle per day (0.5–1.0) and I0 is the initial missile stock. The launch‑vehicle fleet decays exponentially due to air‑strike losses: dV/dt = -λV * V(t) Daily missile loss from airstrikes is a constant L (30–60 missiles/day). THAAD interceptors are consumed at a rate proportional to the number of incoming missiles, with an average of 2.5 interceptors required per missile.

Parameter Estimates

THAAD stock U0: 550–600 units (FY26 budget after 14 % reduction).

THAAD daily production: ≈0.3 units/day.

Interceptors per missile: 2.5.

Iranian missile stock I0: 1,700–2,000 units.

Air‑strike destruction of missiles: 30–60 units/day.

Launch‑vehicle fleet V0: 150–200 units (≈60 % already lost before the conflict).

Launch‑vehicle daily loss rate λV: 0.05–0.10 day⁻¹.

Launch‑vehicle daily launch rate r0: 0.5–1.0 missiles per vehicle per day.

Iranian missile production: ≈15 missiles/day (≈450 per month).

Exhaustion Time Estimates

THAAD depletion (ignoring production) – Assuming a total launch rate of 100 missiles/day (high‑intensity multi‑front scenario), the 550‑unit interceptor pool would be exhausted in ≈2.3 days. At 40 missiles/day the depletion time is ≈5.8 days; at 20 missiles/day ≈11.6 days.

Iranian missile availability – Without air‑strike losses the missile stock lasts 23.5 days. Accounting for 30–60 missiles destroyed per day reduces the effective window to roughly 14 days (≈40 % reduction).

Because launch‑vehicle numbers decay, the launch capacity falls to about 62 % of its initial value by day 7, concentrating the highest pressure on the first three days of the conflict.

Strategic Implications

The critical constraint for Iran is the short window before its launch‑vehicle fleet is heavily degraded; rapid, high‑intensity firing in the first three days is essential for the “Real Commitment 4” strategy. For the US‑Israel side, THAAD interceptors are exhausted within a few days under high‑intensity fire, making the early phase the most vulnerable.

Pre‑emptive strikes that destroy launch vehicles reduce Iranian launch rates but also consume valuable THAAD interceptors, creating a trade‑off that must be quantified.

Globally, the limited pool of advanced interceptors is being allocated across multiple theaters (Middle East, Ukraine, Indo‑Pacific), forcing prioritization decisions.

Quantitative conclusion : In a high‑intensity multi‑front conflict THAAD depletion occurs in ~2.3 days, while Iran’s effective missile window contracts to ~14 days, narrowing the resource ratio from ~10:1 to ~6:1 and highlighting a decisive early‑war period.

Illustrative Figures