Anduril Introduces Steelfin Modular Interceptor to Expand US Missile Stocks

Anduril Industries has introduced Steelfin, a modular, two-stage interceptor missile family designed to address U.S. military inventory shortages. The platform provides a high-volume, cost-effective alternative to legacy defense systems. It is intended to counter threats ranging from low-cost drone swarms to advanced hypersonic missiles, with full-rate production targeted for 2028 and 2029.

"It is an open system, so the ability to fly it with different rocket motors, different seekers, to be able to swap these components out, to be able to reconfigure the system for a range of different threats is a feature that we built into this," said Christian Brose, President and Chief Strategy Officer at Anduril.

Technical Design and Flexibility

The Steelfin system utilizes a common terminal interceptor stage that can be paired with interchangeable boosters of varying diameters. These include 10-inch, 18-inch, and 21-inch options. This modularity allows the military to tailor the missile’s performance to specific mission requirements instead of relying on a single design for every scenario. The system is intended to be compatible with existing military infrastructure, including the M903A2 Patriot launcher, the Mk 41 Vertical Launch System, and fire-control networks like the Army’s Integrated Battle Command System (IBCS) and AEGIS.

Addressing Cost and Inventory Constraints

The U.S. military has faced challenges in recent years due to the depletion of expensive, specialized interceptor stocks when faced with relatively inexpensive adversary threats. Anduril's approach seeks to decouple the cost of the interceptor from the nature of the threat.

"You have the flexibility to be able to engage Shahed-like things with the appropriate-cost missile, as opposed to firing the most exquisite system at the threat every time," said Stephen Milano, Anduril's Vice President for Advanced Projects.

By leveraging commercial manufacturing techniques, Anduril aims to reach a production capacity of several thousand missiles annually. This push for scale is central to the company’s strategy to address long-term inventory depletion issues that have historically affected traditional defense procurement programs.

Strategic Implications for Defense Procurement

The development of Steelfin reflects a shift in the defense industrial base toward open-architecture systems. By allowing for the integration of third-party seekers and motors, the platform is designed to avoid vendor lock-in and enable rapid upgrades as threat technologies evolve. As the project moves toward its 2028 and 2029 production goal, the ability to integrate with existing legacy launchers will be a critical factor in determining its adoption across the U.S. Army and Navy.