UK Navy frigate HMS Iron Duke shadows Russian submarine near French coast amid rising tensions.

The British Royal Navy frigate HMS Iron Duke led a three-day NATO mission to shadow a Russian Kilo-class submarine and its escort near Ushant Island, France. The close encounter highlights rising tensions in European waters and NATO’s focus on maritime vigilance.

London, UK, October 17, 2025 - According to information released by the British Royal Navy on October 14, 2025, the UK Navy frigate HMS Iron Duke led a three-day NATO operation to monitor the Russian Kilo-class submarine Novorossiysk and its escort tug Yakov Grebelsky after the vessels surfaced unusually close to the French coast near Ushant Island, at the western entrance to the English Channel. Conducted from October 7 to 9, the operation formed part of NATO’s wider effort to maintain maritime awareness and readiness amid a rise in Russian submarine activity across key European sea lanes.
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British Royal Navy frigate HMS Iron Duke sails through the English Channel during a three-day NATO operation to monitor and track the surfaced Russian Kilo-class submarine Novorossiysk near the French coast, October 2025. (Picture source: British Royal Navy)

This latest shadowing mission reinforces the growing strategic importance of anti-submarine warfare (ASW) within NATO’s maritime posture. HMS Iron Duke, a Type 23 Duke-class frigate homeported in Plymouth, was specifically deployed for this task due to her pedigree in submarine hunting. Built during the Cold War for the express purpose of tracking Soviet submarines in the North Atlantic, the frigate remains one of the Royal Navy’s most capable ASW platforms. Equipped with the Type 2087 low-frequency active and passive towed array sonar and Type 2050 bow sonar, Iron Duke is able to detect ultra-quiet targets such as the Russian Novorossiysk at significant ranges. Her arsenal includes Sting Ray lightweight torpedoes and a Wildcat HMA2 helicopter from 825 Naval Air Squadron, which extends the ship’s sensor and weapons envelope far beyond the horizon through use of dipping sonar, sonobuoys, and aerial torpedoes.

Iron Duke maintained continuous visual and electronic surveillance on the Russian submarine as it transited through the English Channel into the North Sea. This marked the ship’s second Russian tracking mission in less than two weeks, and her 19th such operation in the past year, a striking testament to both the operational tempo facing British warships and the persistence of Russian undersea activity near NATO waters.

The operation did not occur in isolation. It was part of a coordinated, multinational surveillance chain involving 11 warships from six NATO nations. The tracking effort began in the Mediterranean, where HMS Cutlass of the Gibraltar Fast Boat Squadron first picked up Novorossiysk as it passed through the Strait of Gibraltar. The Russian submarine’s route northwards closely followed European coastal infrastructure and major shipping lanes, placing NATO commands on high alert. Handoffs were conducted between naval units from the Mediterranean through the Bay of Biscay, culminating in Iron Duke's interception near the French coastline.

The British Royal Navy confirmed that Novorossiysk remained on the surface for extended periods during the voyage and was accompanied by the support tug Yakov Grebelsky. While the Russian Ministry of Defence publicly denied any malfunction, citing international navigational norms, NATO officials expressed concern that the prolonged surfacing, especially in rough weather, pointed to possible mechanical issues or fuel limitations. Unofficial NATO intelligence sources in Brussels suggested that the tug may have been deployed in anticipation of propulsion problems or to conduct mid-transit logistics.

Russian undersea movements are always treated as strategically sensitive, but the presence of Novorossiysk in these waters raised specific alarms. As a Project 636.3 Varshavyanka-class submarine, known in NATO nomenclature as the Improved Kilo-class, Novorossiysk is engineered for stealth, endurance, and precision strike. Commissioned in 2014 into Russia’s Black Sea Fleet, the submarine is equipped with six 533mm torpedo tubes and is capable of launching Kalibr-PL cruise missiles with a range of up to 1,500 kilometers. These land-attack missiles place European ports, naval bases, and even inland military targets at risk. NATO naval planners have long warned that such submarines, while conventionally powered, are best suited for littoral infiltration, shadowing allied vessels, or loitering near undersea infrastructure.

In addition to her weapons, Novorossiysk’s low acoustic signature, among the quietest in the world, makes her particularly difficult to track, even for advanced sonar systems. Western submariners frequently refer to the class as "black holes" in the ocean for their ability to disappear from radar and sonar nets. That ability to operate undetected in shallow, congested maritime spaces makes them ideal tools for intelligence gathering, hybrid operations, and strategic intimidation.

By contrast, HMS Iron Duke is part of Britain’s increasingly burdened but still highly capable ASW fleet. The ship’s sonar systems, electronic warfare suites, and her embarked Wildcat helicopter form a layered detection architecture that is specifically tuned to intercept submarines like the Novorossiysk. During the 72-hour operation, British Royal Navy and NATO sources confirmed that Iron Duke maintained constant electronic and visual contact with the Russian submarine despite difficult sea states, underscoring both crew proficiency and platform capability.

Beyond the immediate military implications, the transit of Novorossiysk through such sensitive waters triggers broader security concerns. Her route mirrors several major undersea cable corridors, including transatlantic internet links, commercial data routes, and North Sea energy lines. NATO officials and maritime analysts have repeatedly warned that Russian naval operations in these areas are often dual-purpose. While ostensibly routine or legal, they may also involve seabed reconnaissance, mapping of infrastructure, or signals intelligence collection.

In this light, the role of the British Royal Navy, and specifically platforms like HMS Iron Duke, becomes not only tactical but strategic. These frigates are no longer simply fleet escorts, they are frontline defenders of digital infrastructure, economic stability, and deterrence credibility. As the Royal Navy prepares to phase out Type 23 frigates in favor of the next-generation Type 26 Global Combat Ship, the tempo and complexity of operations like this one point to the enduring importance of ASW in the defense of Europe.

At the time of publication, Novorossiysk has continued her journey into the Baltic Sea under ongoing NATO surveillance. While the Russian vessel remained in international waters, her proximity to European coasts, her prolonged surfaced transit, and the scale of NATO’s coordinated response send a clear message. The Alliance will not tolerate ambiguity or intrusion near its strategic maritime thresholds.

Written by Alain Servaes – Chief Editor, Army Recognition Group
Alain Servaes is a former infantry non-commissioned officer and the founder of Army Recognition. With over 20 years in defense journalism, he provides expert analysis on military equipment, NATO operations, and the global defense industry.