Gulf air defences burn through interceptor stocks

US and Gulf air defences have spent days shooting down Iranian missiles with interceptors that cost more than the threats they are stopping. Business Insider, citing Pentagon figures, reports more than 500 ballistic missiles and 2,000 one-way attack drones launched since US and Israeli operations began on Saturday; Gulf states say they have downed hundreds of missiles and about 1,300 drones.

The bill is not an accounting footnote. A Center for Strategic and International Studies estimate puts interceptor expenditure at about $1.7bn for the first 100 hours of fighting, with a range of roughly $1.2bn to $3.7bn depending on which missiles were used. The arithmetic is built into the systems: a Patriot PAC-3 interceptor is estimated at about $3.7m, and doctrine often calls for firing two per incoming ballistic missile. A single engagement can therefore approach $8m before counting radar hours, reloads, or the aircraft and ships kept on station.

This is the kind of contest where the defender’s job description forces overspending. Airports, LNG plants, desalination facilities and financial districts cannot be “allowed to be hit occasionally” without rewriting the region’s investment case. That makes the interceptor decision less like a trade-off and more like a default: if a radar track looks credible, the launcher fires.

Attackers, meanwhile, can iterate cheaply and at scale. The Shahed one-way drones Iran has used in multiple theatres are typically estimated at $20,000 to $50,000 each, Business Insider notes. Even taking the Pentagon’s numbers at face value, the lower-end cost of 2,000 drones is about $40m — less than the price of a dozen PAC-3s, or fewer than four THAAD interceptors, which are estimated near $13m apiece. When a cheap drone forces a premium interceptor, the attacker is effectively buying the defender’s inventory depletion.

The second-order effects are already visible across the Gulf. Insurance and shipping markets have been repricing risk around Hormuz; airlines have rerouted or suspended flights; and logistics hubs that sell reliability as a product have discovered that reliability now depends on finite missile stocks and the willingness of outside powers to replenish them. The Pentagon says it surged “every counter-UAS system possible” to the region, but the critical constraint is not creativity — it is magazine depth.

What looks like air defence is also a procurement pipeline. Interceptors are manufactured in limited quantities, ordered years in advance, and politically allocated. In a prolonged exchange, the question shifts from “can we stop this wave” to “who gets the next shipment”, and which cities, bases, and export terminals are deemed worth the shot.

In the early hours of the war, the Gulf states advertised successful interceptions as proof that the system works. After several days, the same numbers read like a burn rate.