Anduril Steelfin: a new interceptor family aimed at the cost of the PAC-3

US company Anduril unveiled Steelfin on Monday, October 12, 2026, a new family of interceptors designed to counter drones, aircraft, cruise missiles, ballistic missiles and hypersonic threats. The company’s goal is to do so at a fraction of the cost of today’s interceptors. The unveiling coincided with the annual AUSA meeting and exhibition in Washington.

Anduril said one version of Steelfin meets the requirements of the US Army’s Future Interceptor programme, in which Lockheed Martin is proposing the PAC-3 Edge (see PAC-3 Edge: Lockheed Martin unveils the new Patriot interceptor). In its post on X the company wrote: “Today’s missile defense model does not scale. The modern fight demands an interceptor that can match cost and capability to threat.”

Two stages, and a common second stage

Steelfin has a two-stage design. The first stage is a solid-fuel booster that determines range and performance. The second stage is the interceptor itself and is common to all versions, with the same body, electronics, software, flight systems and interfaces. Depending on the booster, versions are designed for speeds from supersonic to very high hypersonic and for intercepts from low altitude to the upper atmosphere.

The second stage can carry different sensors, such as radar and infrared seekers, without a design from scratch. All versions will be built on the same production line, with common tooling, technicians and facilities, and output of each version can be raised as demand rises. Anduril says it plans to reach several thousand missiles a year.

Three booster diameters

It has different boosters with diameters of 10, 18 and 21 inches. With them the family covers sizes comparable to Lockheed Martin’s PAC-3 (10 inches), and to Raytheon’s THAAD and SM-3 Block IIA (21 inches). The smallest version appears to target the Future Interceptor, which would fill the range gap between the PAC-3 MSE and the THAAD interceptor.

Anduril’s Stephen Milano said the PAC-3-role version offers about 80% of PAC-3’s capabilities at less than half the missile’s cost. He added that a more powerful configuration could take on THAAD-type missions at significantly lower cost. The company has not given unit prices. Milano added that the low cost makes it possible to counter Shahed-type drones with a cost-effective interceptor.

Launchers and battle management

According to Anduril, Steelfin versions are compatible with the PAC-3’s M903A2 launcher, the ships’ Mk 41 vertical launching system, the Typhon system, and new containerised launch systems. They are also designed for integration into existing battle management systems such as Aegis and IBCS. Open interfaces allow the use of off-the-shelf commercial components and competing subsystems from multiple suppliers.

What has not been stated

The company has completed tests with representative vehicles, without powered flight. Flight tests of the versions are expected to begin in 2027, and no date for entering service has been announced. Range, intercept altitude, speed, seeker type and warhead have not been given, and no specific customer is named: Anduril says only that it has invested alongside “multiple customers”. The performance and cost figures are claims by the company.