On Monday, divers with Yemen's Houthi rebel group found and captured an autonomous submersible that allegedly belongs to the Saudi-led coalition on the opposing side of Yemen's civil war. The device shows signs of long-term use and wear, and it has the manufacturers' markings and physical appearance of a REMUS 600, a popular design that is in service with the U.S. Navy and the Royal Navy.
"Yemen Navy and Coastal Defense capture [sic] a spy REMUS 600 submarine belonging to the U.S.-Saudi aggression coalition against Yemen, inside the Yemeni territorial waters in the Red Sea," a Houthi social media channel asserted.
The Remote Environmental Monitoring Unit System (REMUS) 600 is an intelligent marine robot manufactured by Hydroid, a division of Kongsberg, with a service history dating back to the 1990s. It features a terrain avoidance sonar, wet and dry payload bays, and a maximum rated depth of nearly 2000 feet. It is used by oceanographers for research purposes in marine biology, environmental monitoring and physical oceanography; by commercial operators for environmental monitoring, hydrography and oil and gas applications; and by military users for mine countermeasures and surveillance. It operates autonomously on a preprogrammed course to carry out its mission.
Two variants are in use by the U.S. Navy. The Mod 2 Kingfish, a high-endurance version with improved sonar, has been deployed in the Middle East for search, mapping and mine countermeasures. Three Littoral Battlespace Sensing variants have also been acquired by U.S. Space and Naval Warfare Systems Command in San Diego.
Naval mines and have been a particular concern in the Yemeni waters of the Red Sea, raising the importance of mine countermeasures operations. Last May, the Saudi Navy said that it had found several improvised mines in the waters off Midi, a port just sound of the Yemeni-Saudi border. Several months earlier, a Yemeni Coast Guard ship hit a mine near the port of Mokha, killing two servicemembers and wounding eight more. The threat extends to merchant shipping as well: last March, the U.S. Office of Naval Intelligence issued a warning to mariners regarding the possible presence of naval mines in waters off the west coast of Yemen.