February 23, 2024 · 🇮🇷 Report MIW

A Houthi Undersea Capability

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On February 17, 2024, a CENTCOM statement indicated that U.S. naval forces conducted a self-defense strike against a Houthi unmanned underwater vehicle (UUV). With continued U.S. air defense and strike operations degrading Iranian-backed Houthi air power, Houthi forces are seeking an undersea warfare capability in order to further disrupt Red Sea commercial traffic, and to strike U.S. or partner warships.


▶︎ The text of the CENTCOM statement suggests that the UUV was destroyed on shore, prior to deployment, and not interdicted as an inbound threat.

▶︎ Iran is developing several UUV variants, but individual vehicle capabilities are unknown.

▶︎ The Islamic Revolutionary Guard Corps Navy (IRGCN) likely possesses an operational hybrid UUV/torpedo with high endurance, long range, and light or heavyweight warhead capacity.

▶︎ The IRGCN likely possesses an operational large displacement unmanned underwater vehicle (LD-UUV), that could be used as a remotely controlled one-way attack (OWA) platform.

▶︎ The IRGCN vehicles are likely powered by lithium ion (Li-ion), nickel-metal hydride (NiMH), or lead-acid batteries, providing them with long range, but with less propulsive power than a standard torpedo.

▶︎ The vehicles are likely guided by inertial navigation and/or remote operation via a retractable communications mast equipped with an electro-optical sensor.

▶︎ If unguided, or guided by inertial navigation only, the vehicles would be effective primarily against stationary or slow moving targets.

▶︎ It is possible the vehicles utilize wake homing guidance.

▶︎ In order to maximize hit probability, the vehicles would likely be launched in salvos from flotillas of Houthi fast boats, from the coastline of Houthi-controlled areas of the Yemen mainland, or from the western shores of Houthi-controlled islands in the Red Sea.

▶︎ Vehicles would likely be held in reserve for use against U.S. or partner warships in order to generate significant operational, psychological, and political effects.

During a weapons unveiling ceremony in March, 2022, the Islamic Revolutionary Guard Corps Navy (IRGCN) revealed the existence of a purported loitering torpedo program.


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In May, 2023, OSINT reports indicated the existence of an Iranian large displacement unmanned underwater vehicle (LD-UUV).


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Although Iranian UUV capabilities are difficult to estimate, comparable Western programs can provide insight into possible Iranian systems. NOTE: Data have been collected from manufacturer spec sheets, and are often approximate. Vehicle length can vary according to payload modules, and endurance/range will vary according to payload weight and "hotel load" - power consumption not related to propulsion (sensors, onboard processing).

REMUS-620 (Lightweight) - Huntington Ingalls

In length and diameter, the REMUS-620 is roughly comparable to a lightweight torpedo.

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Length: 3.1 to 4.8 meters
Diameter: 32.4cm (12.75 inches)
Depth: 600 meters (1969 feet)
Weight: 210-411 kg (464-907 lbs)
Speed: 3 knots
Energy: Lithium Ion
Max Range: 205NM depending on battery payload

(NOTE: A REMUS-600 was seized by Houthi forces off the coast of Yemen in 2018. The vehicle was likely handed over to the IRGCN and reverse engineered to inform UUV development.)

Bluefin-21 (Heavyweight) - General Dynamics


In length and diameter, the Bluefin-21 is roughly comparable to a heavyweight torpedo.

Length: 4.9 meters (16.2 feet)
Diameter: 533mm (21 inches)
Depth: 4500 meters (14,763 feet)
Weight: 750 kg (1650 lbs)
Speed: Up to 4.5 knots
Energy: Lithium Polymer
Max Range: 75NM (25 hours @ 3kts)

Hugin Endurance (LD-UUV) - Kongsberg

The Hugin Endurance is roughly comparable to the IRGCN LD-UUV.

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Length: 11 meters (36.3 feet)
Diameter: 1.2 meters (3.9 feet)
Depth: 6000 meters
Weight: 8000 kg (17,636 lbs)
Speed: 8 knots
Energy: Lithium Ion
Max Range: 1200NM (25 hours @ 3 knots)

In late January, a U.S. Coast Guard ship intercepted a vessel in the Arabian Sea that originated in Iran and was bound for a Houthi-controlled area of Yemen. Onboard was a cache of weapons and supplies, which included included UUV components.


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There is no information regarding the hybrid UUV/torpedo or LD-UUV guidance, power/propulsion, or warhead size.

Possible Prior Use

One of these vehicles, or another of similar construction, may have been used in the May, 2019, attack on commercial vessels anchored in the Gulf of Oman.


Concepts of Operation (CONOPS)

Vehicle deployment and operation would be driven by its dimensions, guidance system, range, and payload.


It is unlikely that a heavyweight vehicle could be launched from a fast boat, as its size and mass require heavy lift infrastructure for over the side deployment.


However, it is possible that a boat could be configured to launch a heavyweight vehicle via a transom cutout and makeshift ramp system.

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Houthi operators would deploy vehicles from fast boats or shore points with direct access to shipping lanes or operational areas of U.S. and partner warships.

Indications and Warning

Several activities and operations would indicate the means and method of a Houthi undersea attack:

Countermeasures and Defense


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