Iran claims capture of US Navy MK 18 Mod 2 Kingfish mine-hunting underwater drone in Strait of Hormuz.

Iran's Islamic Revolutionary Guard Corps (IRGC) Navy announced the seizure of a U.S. Navy MK 18 Mod 2 Kingfish autonomous underwater vehicle within the Strait of Hormuz. The incident marks the second reported recovery of an American unmanned underwater system by Iranian forces during the ongoing regional conflict. Technical specialists are currently examining the recovered platform for stored mission data and sonar payload configurations.

The MK 18 Mod 2 Kingfish is a battery-electric mine-countermeasure system measuring approximately 3.5 meters in length and weighing up to 272 kilograms, utilizing side-looking synthetic aperture sonar for seabed mapping. While Iranian authorities claim the platform was captured through electronic warfare capabilities, the U.S. Central Command (CENTCOM) has rejected the assertion and maintained that all operational drone assets remain under positive control.

Related topic: Iran captures disabled US Anduril Dive-LD military underwater drone in Strait of Hormuz

Iran claims it captured an MK 18 Mod 2 Kingfish mine-countermeasure UUV in the Strait of Hormuz, which, if confirmed, would mark Iran’s second recovery of a U.S. Navy underwater drone in September 2026, after the Anduril Dive-LD. (Picture source: X/Irgcspeaker and US DoD)

On September 27, 2026, IRGC spokesman Second Brigadier General Hossein Mohebbi announced that Iran had captured a U.S. MK 18 Mod 2 Kingfish autonomous underwater vehicle (UAV) in the Strait of Hormuz, potentially placing U.S. Navy stored mission data in Iranian hands. Iran initially called it a REMUS 600 before updating the identification, as the Kingfish is the U.S. Navy mine-countermeasure derivative of the commercial REMUS 600, retaining its 32.4-cm diameter and 600-m depth rating. IRGC spokesman Second Brig. Gen. Hossein Mohebbi called it Iran's second U.S. underwater vehicle recovery in September and said specialists were extracting its data, while CENTCOM spokesman Capt. Tim Hawkins rejected the claim and said U.S. forces retained positive control of all operational drone assets.

The claim follows Iran's September 8 recovery of an Anduril Dive-LD, which Washington acknowledged had malfunctioned before recovery and carried neither classified sonar nor radar equipment. The Kingfish would represent a different case because its primary function is detecting, classifying, and mapping naval mines before crewed forces enter suspected minefields. According to available information, the MK 18 Mod 2 Kingfish is a battery-electric UUV measuring roughly 3.5 m long and 32.4 cm in diameter, with a mass of 240 to 272 kg, although modular REMUS 600 configurations can reach roughly 4.3 m depending on installed battery and payload sections. Maximum speed is normally 5 kt, with some Kingfish figures reaching 6 kt, while the standard 3-kt cruise regime prioritizes sonar coverage and endurance.

A long-endurance REMUS 600 configuration can operate for nearly 70 hours and has a cited maximum range of 286 nmi (530 km), whereas the later REMUS 600M reaches up to 72 nmi (133 km) at 3 kt with standard sensors active. The latter carries two 5.4-kWh lithium-ion battery trays totaling 10.8 kWh, illustrating the direct trade between battery volume, sensor load, payload, and endurance. The Kingfish therefore does not have one fixed range or endurance figure: its mission radius likely changes with configuration, speed, and power consumption. The Kingfish conducts search-classify-map missions against floating, moored, bottom, and buried mines using dynamic-focus, side-looking sonar that scans strips of seabed on both sides of its programmed track. Its Small Synthetic Aperture Sonar Module (SSASM) increases swath width and image resolution and adds buried-target detection for mines obscured by sand or mud.

Other equipment includes a downward-looking camera, a conductivity-temperature-depth (CTD) sensor, Acoustic Doppler Current Profiler, beam attenuation meter, fluorometer, turbidity sensor, and pencil-beam obstacle-avoidance sonar. Navigation combines inertial equipment, compass, Doppler velocity log, acoustic Doppler measurements, and P-code GPS, while communications use an acoustic modem underwater and Iridium SATCOM and radio after surfacing. Because high-resolution sonar produces substantially more data than an acoustic link can efficiently transmit, imagery is stored aboard for recovery and processing through COIN and the Mine Warfare and Environmental Decision Aids Library. The system's Gulf deployment began from a specific Fifth Fleet requirement raised in December 2011, with the first Kingfish capability reaching the theater in July 2012, followed by additional waves in February and October 2013.

Before deployment, a 15-day mock operation off Panama City Beach included more than 30 sorties from waters exceeding 20 nmi (37 km) offshore, with three or four UUVs operating for eight hours per day. Interestingly, the area reproduced the temperature, salinity, depth, and water-clarity conditions affecting sonar performance of the Persian Gulf. The Kingfish consequently shifted the initial mine search from divers or crewed vessels to a 240- to 272-kg autonomous sonar carrier that could survey an uncleared area and return with georeferenced contacts. The U.S. Navy has maintained continuous MK 18-family support to Fifth Fleet mine-countermeasure operations since July 2012, giving the underwater system more than 14 years of connection to the theater by September 2026. 

At more than 240 kg, each Kingfish requires mechanical handling and is normally deployed from an 11-m rigid-hull inflatable boat (RHIB) fitted with dedicated launch-and-recovery equipment. One RHIB can carry two MK 18 Mod 2s, allowing sequential sorties, separate search sectors, or continued operations while one vehicle is serviced. Operators program waypoints and survey tracks before launch; the UUV then searches autonomously at roughly 3 to 5 kt, returns for recovery, and transfers its sonar and environmental data for analysis. Early Fifth Fleet deployments used contractor crews led by a government civilian under Fifth Fleet EOD and mine-countermeasure command arrangements before transition toward military operators.

The Kingfish can also be crane-handled from larger ships and has operated with vessels including the Independence-class littoral combat ship USS Charleston, allowing the supporting ship and personnel to remain outside individual mine-search tracks. Program-of-record production began through Hydroid in 2012 and ended on February 3, 2023, after more than 90 MK 18 Mod 2s had been delivered to the U.S. Navy. A 2019 support contract was initially valued at $15.8 million and could reach $84 million with options, while Hydroid received another $74.7 million in April 2021 for Increment II payload upgrades scheduled through April 2026. That modernization targeted mine detection and localization in mud, sand, and turbid water, including buried targets, rather than increases in vehicle speed or depth.

The U.S. Navy had already selected Leidos in July 2022 to develop the Viperfish as the next-generation Medium Unmanned Undersea Vehicle (MUUV) for expeditionary mine countermeasures. A genuine Iranian recovery would therefore involve a mature system with an 11-year production run, more than 90 Navy vehicles, and a recent $74.7 million sensor modernization program. An intact vehicle's principal intelligence value would be its payload configuration and non-volatile memory. Stored information could include side-scan or synthetic-aperture sonar imagery, waypoints, search-lane spacing, headings, depth, environmental measurements, and time-tagged navigation history, potentially revealing which parts of Hormuz were searched and which contacts were detected.

GPS fixes obtained while surfaced, inertial estimates, Doppler velocity measurements, and acoustic navigation inputs could reconstruct part of the sortie, while hardware examination could expose the installed sonar, acoustic modem, navigation equipment, battery arrangement and external interfaces. The value would be higher if the vehicle carried Increment II or SSAM hardware and recoverable recent mission data. Iran's electronic warfare claim does not establish how the vehicle was obtained because GPS, Iridium and radio links require surface access, whereas submerged operation relies mainly on autonomous navigation and acoustic communication; disruption of a functioning Kingfish would therefore have different implications from recovery after battery, propulsion or navigation failure like the Anduril Dive-LD.

The claimed recovery occurred while Hormuz remained severely disrupted by the conflict that began in February 2026, making mine reconnaissance directly relevant to attempts to maintain or restore maritime corridors. By late September, vessel traffic averaged roughly 18 transits per day over 10 days and had fallen to nine on some days, while before the conflict roughly 20 million barrels per day of oil normally passed through the strait. Foreign Minister Abbas Araghchi said on September 25 that normal passage could be restored within seven days if Washington implemented conditions in the earlier U.S.-Iran memorandum of understanding, but President Donald Trump rejected the proposal on September 26. Military activity continued in parallel, including an Iranian anti-ship cruise missile strike on September 14 that injured eight U.S. Marines aboard a vessel transiting the strait. Iran reiterated after the September 27 incident that Hormuz remained closed to unauthorized movements, placing Kingfish operations within a concrete contest between U.S. efforts to map possible mine threats and Iranian efforts to monitor and restrict underwater and surface movement through the chokepoint.

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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, South Korea, Türkiye, and Belgium. His analyses go beyond the facts, providing context, identifying key actors, and explaining why defense news matters on a global scale.