Anduril Unveils Steelfin: A Modular Missile Family Built to Undercut THAAD’s Cost

Quick take: Defense technology company Anduril unveiled a modular family of surface-to-air missiles called Steelfin on October 12, 2026. The company says a high-end variant could perform the entire THAAD mission at a fraction of that interceptor’s cost.

One architecture, many missions

Anduril president and chief strategy officer Christian Brose describes Steelfin as “an open system.” The family shares a common airframe, avionics, software, flight-control system and interfaces, while swapping in different rocket motors and seekers depending on the mission. Each missile uses a two-stage design: a booster paired with a terminal interceptor.

According to Brose, Anduril is currently working with 10-inch, 18-inch and 21-inch boosters, alongside dual-pack and quad-pack configurations sized for the Mk 41 vertical launch system. Range and altitude will vary with booster size. The family will offer both hit-to-kill and blast-fragmentation terminal interceptors.

What it’s meant to stop

Steelfin’s intended missions span point defense, lower-tier integrated air and missile defense, and upper-tier ballistic missile defense. It is designed against cruise, ballistic and hypersonic threats, though it stops short of exo-atmospheric midcourse interception, the realm of systems like SM-3.

Steve Milano, who leads Anduril’s Air Dominance and Strike business, says the most capable Steelfin configuration would sit between the PAC-3 MSE and THAAD in performance. By his figures, it would deliver the full THAAD mission at a fraction of the cost, and roughly 80 percent of that mission in a PAC-3-like configuration for under half the price. Against the Navy’s SM-2 in ship defense, Milano claims over 80 percent of the capability at about a third of the cost.

Where the price comparisons come from

The reference prices cited alongside these claims are roughly $15.5 million per THAAD interceptor, about $5.3 million for a PAC-3 MSE per the FY2027 Army budget, and around $2.5 million for an SM-2 Block IIIC. These figures come from Anduril’s own comparison and are not independently audited, so actual contract prices could differ once competitions conclude.

On manufacturing, Anduril says near-term capacity is planned at several thousand missiles a year, built to scale up or down as demand shifts. Variants will share production lines, with mission-specific boosters and terminal sections added during final assembly.

A crowded field of cheaper interceptors

Steelfin enters a market already filling with low-cost interceptor proposals. Lockheed Martin debuted its PAC-3 ACE at the Farnborough Airshow in July 2026, pricing it at roughly half the cost of the current PAC-3 MSE. The US Army itself solicited a Patriot-compatible interceptor priced under $1 million per round back in May 2026 — a different, cheaper category from Lockheed’s separate PAC-3 Edge, which targets hypersonic threats at the high end.

Anduril has no prior track record building or fielding a surface-to-air missile; its relevant experience comes mainly from the Roadrunner counter-air system. The company says it has spent several years developing Steelfin with funding from multiple customers. Ballistic testing with representative vehicles is complete, and flight tests of the different variants are planned for 2027.

Launcher and fire-control compatibility

Planned launcher compatibility includes the M903A2 used by newer PAC-3 variants, the Mk 41 VLS, the Typhon launcher, and emerging containerized launch systems. On the fire-control side, Anduril is targeting compatibility with Aegis and the US Army’s Integrated Battle Command System (IBCS), aiming to let Steelfin plug into both naval and land-based networks rather than being tied to one platform.

Brose says Anduril believes Steelfin “will be a critical component of US and allied inventories.” The company has not named which governments or services are currently evaluating the system, so export interest remains speculative for now.

Sources

• The War Zone (TWZ), “Anduril Unveils Steelfin Family Of Modular Surface-To-Air Missiles,” October 12, 2026 — used for the architecture, variants, pricing comparisons and official quotes.
• Breaking Defense, coverage of the Steelfin unveiling around AUSA 2026, October 2026 — used for independent confirmation.
• Trade press coverage of Lockheed Martin’s PAC-3 ACE and the US Army’s low-cost interceptor requirement — used for competitive context.