Anduril's Steelfin bets on mass-produced air defence

On 12 October 2026 Anduril unveiled Steelfin, a family of mass-producible surface-to-air interceptor missiles. It is the company's first surface-to-air missile, and a direct challenge to the incumbents that supply Patriot, THAAD and Standard Missile interceptors.

Steelfin uses a common two-stage architecture: a first-stage booster that sets range and performance, and a second-stage terminal interceptor that shares the same airframe, avionics, software, flight control and interfaces across all variants. Boosters of 10, 18 and 21 inches are being considered, with hit-to-kill and blast-fragmentation interceptors on offer.

One line, many missions

The family is meant to cover point defence, lower-tier integrated air and missile defence and upper-tier ballistic missile defence, against cruise, ballistic and hypersonic threats. Because variants share components, Anduril says it can switch production between them on the same line, with mission-specific boosters and seekers added at final assembly. Near-term production is planned at several thousand missiles a year.

Steelfin is designed to fit existing launchers, including the M903A2 used for PAC-3, the Mk 41 vertical launch system, Typhon and containerised launchers, and to integrate with AEGIS and IBCS fire control. Ballistic testing with representative air vehicles is complete, and flight testing is scheduled to start in 2027.

In air defence, the cost-exchange ratio has become a strategic problem, not a budgeting detail.

The cost argument

Anduril has not published prices, but has made bold claims: a PAC-3-class version delivering about 80% of the mission at under half the cost, more than 80% of an SM-2's capability for a third of the price, and a higher-end variant that could perform THAAD-type missions at a fraction of the cost. For reference, the PAC-3 MSE costs about $5.3 million in the FY2027 Army budget, THAAD about $15.5 million and an SM-2 Block IIIC about $2.5 million. The Army is seeking a Patriot-compatible interceptor below $1 million.

Part of a wider munitions push

Steelfin follows Anduril's May 2026 framework agreement with the US Department of War for at least 3,000 surface-launched Barracuda-500M cruise missiles over three years, at a rate of at least 1,000 a year, with production eventually moving to Arsenal-1, its planned five-million-square-foot factory near Columbus, Ohio. The company is also investing in solid rocket motor capacity in Mississippi. The pattern is consistent: low-cost, modular munitions designed for volume.

Why it matters

Recent conflicts in the Middle East and Ukraine have consumed interceptor inventories far faster than they can be replaced. Allies in Europe, the Gulf and Asia face the same arithmetic. A credible second source of affordable interceptors would change procurement plans and put pressure on established suppliers, which are themselves working on cheaper variants such as Lockheed Martin's PAC-3 ACE.

What to watch

Flight-test results in 2027; whether the cost claims hold once production starts; the first customer commitments, which Anduril says are under discussion with several unnamed customers; and export interest from allies that operate Patriot, Aegis or Typhon and need deeper magazines quickly.