US Navy presents SM-2 Block IIIC/CU missile upgrade to improve medium-range air defense.

The SM-2 Block IIIC/CU medium-range surface-to-air missile was displayed at the Surface Navy Association 2026 symposium, providing a detailed look at the latest Standard Missile-2 configuration used by the U.S. Navy.

As reported by 笑脸男人 on January 17, 2026, the SM-2 Block IIIC/CU medium-range surface-to-air missile was displayed at the Surface Navy Association 2026 symposium, providing a detailed look at the latest Standard Missile-2 configuration used by the U.S. Navy. The variant, also known as RIM-66P, incorporates a hybrid semi-active and active radio-frequency seeker, updated control features, and revised internal electronics. The design focuses on extending service life while maintaining compatibility with existing naval launch systems.
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The SM-2 Block IIIC adds the new active radar seeker and control upgrades, while the Block IIICU replaces the SM-2's internal electronics to ensure long-term production and sustainment. (Picture source: X/笑脸男人)

The Block IIIC/CU, also designated as RIM-66P by Raytheon, reflects the transition of the SM-2 from older semi-active guidance concepts toward a new hybrid architecture incorporating active radio-frequency sensing, updated control features, and revised internal electronics. This variant, positioned to remain a core element of naval medium-range air defense against anti-ship cruise missiles and tactical aircraft, is intended to extend the service life of the missile through targeted upgrades rather than a complete redesign.

The SM-2 Block IIIC was developed as a rapid prototyping effort, with an interim capability declared in November 2022 and expectations for fielding in the second quarter of fiscal year 2024. Evaluation activities completed in fiscal year 2023 included live missile firing, modeling and simulation work, and cyber-focused assessments, conducted to support early fielding decisions rather than full operational effectiveness determinations. The follow-on Block IIICU is structured as an Acquisition Category II program, with approval to enter Milestone B in April 2023 and initial operational test and evaluation planned for fiscal year 2027. This phased approach reflects the incremental integration of updated guidance electronics while maintaining continuity in fleet air defense coverage.

The SM-2 Block IIIC and IIICU are defined by the replacement of the legacy semi-active radar homing seeker with a dual-mode semi-active and active radio-frequency seeker derived from the SM-6 Block I. This change enables engagements with reduced dependence on continuous radar illumination from the launching ship, supporting higher engagement capacity and more flexible fire control during complex air defense scenarios. Both variants retain the established SM-2 propulsion concept and general dimensions, preserving compatibility with existing launch systems and shipboard integration. Within fleet operations, the missile is intended to support both self-defense and area air defense missions, including operation within Naval Integrated Fire Control-Counter Air (NIFC-CA) engagements that allow the use of off-board sensor data.

The SM-2 Block III missile has a launch mass of about 707 kg, a length of about 4.72 m, a body diameter of about 34.3 cm, and a wingspan of about 1.07 m, retaining a dual-thrust solid-fuel rocket motor for sustained high-speed flight. The Block III achieves speeds up to about Mach 3.5 and is credited with an engagement range from about 74 km to 170 km, depending on profile, with an operational ceiling above 25,000 m. Guidance combines inertial navigation with command midcourse updates and monopulse semi-active radar homing in the terminal phase, with later Block IIIB variants also integrating an infrared seeker for improved performance against low-altitude or low-signature targets. The warhead is a blast-fragmentation type with radar and contact fuzing, optimized for engagement of aircraft and anti-ship cruise missiles.

The SM-2 Block IIIC/CU displayed includes multiple external and internal changes aimed at improving control and compatibility with updated guidance electronics. Notable airframe updates include a redesigned dorsal fin and the integration of a thrust-vectoring jet tab assembly (JTA) that manages missile attitude and trajectory as it exits the launcher and transitions into powered flight. These features are intended to improve controllability during the launcher-egress phase, a critical point for vertical launch operations. Internally, the Power, Control, and Telemetry (PC&T) section and the Steering Control Section (SCS) used are derived from the earlier SM-6 Block I architecture. Under hardware modifications, the PC&T section replaces a G-switch (acceleration-based mechanical switch) with a new separation Circuit Card Assembly (CCA) and incorporates modified W4 harnesses, reflecting a shift toward modular electronics assemblies aligned with newer missile standards.

Further hardware notes detail how attachment and control interfaces bridge legacy SM-2 elements with SM-6-derived components. The SCA (Structural Control Assembly) modification creates a hybrid of the SM-2's GFM (Guidance and Flight Module) and the SM-6's CCS (Command and Control System) inner attachment arrangements, indicating a structural and mechanical integration between the two missile families. The SCS changes include modifying a bolt pattern derived from the SM-2 DTM (DTM, Digital Telemetry Module) and replacing a CCS actuator switch to interface with the redesigned Jet Intake Assembly (JIA). Collectively, these changes suggest coordinated updates across guidance, control, and early-flight steering systems to ensure functional integration of new and legacy elements.

In summary, the Block IIIC is the capability leap, introducing the active RF seeker and control changes, while the Block IIICU is the sustainment and electronics-hardening step, ensuring that the Block IIIC design remains producible, supportable, and compatible with updated guidance hardware over the long term. The distinction of the Block IIICU lies in the integration of an upgraded Guidance Section Electronics Unit (GS EU) and target detection device derived from the SM-6 Block IAU, addressing obsolescence while retaining the Block IIIC seeker and control changes. There are no changes to the legacy warhead or fuzing method used on SM-2 Block IIIC and IIICU, although the packaging of the warhead within a modified airframe is noted as a factor requiring assessment for lethality effects.

Written by Jérôme Brahy

Jérôme Brahy is a defense analyst and documentalist at Army Recognition. He specializes in naval modernization, aviation, drones, armored vehicles, and artillery, with a focus on strategic developments in the United States, China, Ukraine, Russia, Türkiye, and Belgium. His analyses go beyond the facts, providing context, identifying key actors, and explaining why defense news matters on a global scale.