Surface Ship Torpedo Defense

The Surface Ship Torpedo Defense (SSTD) program, outlined under Program Element PE 0603506N, is a Navy research, development, test, and evaluation initiative focused on providing layered torpedo defense capabilities for surface ships. The primary objective of SSTD is to enhance ship survivability against current and emerging torpedo threats through a combination of detection, warning, and countermeasure systems. The program is managed under the Advanced Component Development & Prototypes (ACD&P) budget activity and encompasses several major efforts, including the AN/SLQ-25 (NIXIE) system, Torpedo Warning System (TWS), Countermeasure Anti-Torpedo (CAT), and Acoustic Device Countermeasure (Surface ADC MK2).

The AN/SLQ-25 (NIXIE) system is a towed acoustic countermeasure designed to decoy incoming torpedoes away from surface ships. The FY 2026 budget supports capability improvements to the NIXIE system, particularly through software development and testing, as well as hardware enhancements to meet the requirements of the forthcoming Hardkill (HK) system. These upgrades aim to integrate advanced detection and fire control functionalities, ensuring the NIXIE system remains effective against evolving torpedo technologies.

The Torpedo Warning System (TWS) provides surface ships with the ability to detect, classify, and localize incoming torpedo threats. TWS is being integrated into the NIXIE tow system, with ongoing research and development efforts to enhance its alertment and fire control capabilities. FY 2026 funding continues support for TWS sustainment on two aircraft carriers and advances the development of a launcher capable of deploying both the Compact Rapid Attack Weapon (CRAW) and ADC MK2 countermeasures. The goal is to deliver a fire control solution that can cue hardkill weapons in response to detected threats.

Development of the NIXIE Hardkill (HK) System is a central focus for FY 2026, aiming to provide a robust hardkill capability against torpedoes. This system will integrate the improved NIXIE 25E tow array, TWS, and a launcher for the Mk 58 CRAW and ADC MK2 devices. Development activities include prototyping and testing the torpedo alertment and fire control functionality, winch improvements to support enhanced tow cables, and the design of a modular launcher system. The HK system is planned for installation on over 165 surface ships, representing a significant expansion of the Navy's torpedo defense posture.

Countermeasure Anti-Torpedo (CAT) and Acoustic Device Countermeasure (ADC) efforts have transitioned, with CAT sustainment ending in FY 2024 and its materials being incorporated into the CRAW program. The ADC MK2 MOD 6/8 and MK5 series continue to be supported as part of the integrated launcher development. These countermeasures are intended to provide both softkill and hardkill options, increasing the flexibility and effectiveness of shipboard torpedo defense.

The SSTD program leverages technologies and innovations from Future Naval Capabilities (FNC), Small Business Innovative Research (SBIR), and other RDT&E initiatives. New hardware and software are evaluated in representative acoustic environments and through simulations to ensure their effectiveness against projected threats. The modular and COTS-based design of the AN/SLQ-25E allows for incremental capability insertions, enabling the Navy to rapidly field improvements as they are developed and tested.