A renewed Iran war would test already-diminished US interceptor inventories, the Center for Strategic and International Studies (CSIS) warned in a July 27 analysis by Mark F. Cancian and Chris H. Park, as combat operations since a ceasefire collapse have drawn further on stocks that were already stretched by the war's first phase.

The story of how those stocks got this low, and what Washington and its allies are now doing about it, runs through three linked developments over the past week.

The depletion: a third of Patriots, half of THAAD

CSIS estimates the US now holds roughly 759-827 Patriot interceptors and 234-278 THAAD interceptors, down from about 2,330 and 452 respectively before the war — a fall of around a third for Patriot and roughly half for THAAD. "The air defense campaign has been largely successful with high — though not perfect — interception rates," CSIS found, but sustaining that rate has required extensive use of interceptors even as Iranian launches have continued at a lower rate than before the ceasefire. Replenishing high-end stocks at this scale could take years, CSIS and outside analysts warn, despite expanded production efforts, leaving limited capacity for other contingencies if demand stays high.

The US Army has awarded Lockheed Martin (NYSE: LMT) a contract worth up to $58.6bn to produce PAC-3 MSE interceptors, converting an earlier one-year, $4.7bn deal into a seven-year procurement plan covering fiscal years 2026-2032, Reuters reported. Lockheed says the funding will let it triple PAC-3 MSE production capacity by the end of 2030 and grow headcount at its Camden, Arkansas plant by half, to around 1,850 jobs from 1,200; the company is investing a further $8bn-9bn through 2030 to modernise more than 20 US facilities, including new munitions centres in Alabama and Arkansas.

Even as it rebuilds its own stockpile, Boeing (NYSE: BA) — which manufactures the PAC-3 seeker head — has refused to license Ukraine to produce the component itself, Die Welt's Christoph Wanner reports. The Ka-band AESA seeker is the central bottleneck in the whole system, and Boeing needs around seven years to triple its own output even with expansion under way; building a full Ukrainian supply chain, factories and licences from scratch would take longer still.

The refusal leaves Kyiv's own request — 300 Patriot missiles before winter, which President Volodymyr Zelenskiy has raised directly with President Donald Trump — competing for a supply that Washington itself is now racing to rebuild for its own coalition commitments in the Gulf.