Breaking News: Royal British Navy Closely Monitors Surfaced Russian Submarine Signalling Power in North Sea.

On July 2nd, 2025, Royal British Navy helicopters and the Portsmouth-based patrol ship HMS Mersey closely monitored a surfaced Russian Kilo-class submarine transiting through the North Sea and English Channel, as reported by the British Navy. This incident underlines the Royal British Navy’s vigilance at a time of rising Russian naval assertiveness around the UK’s maritime approaches. The sighting and shadowing of the submarine once again signal that the North Sea remains an active and contested theatre, demanding constant situational awareness and readiness from British forces.
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By surfacing the Novorossiysk submarine during transit, Russia may well be signalling an intention to remind the UK and NATO that Russian submarines can and will assert presence in waters that are vital to Europe’s energy flows and undersea infrastructure (Picture source: Royal British Navy)

In this latest operation, HMS Mersey, a River-class offshore patrol vessel designed for surveillance, interdiction and general maritime security, was joined by a Wildcat helicopter from 815 Naval Air Squadron and a Merlin Mk2 helicopter from 824 Naval Air Squadron, both of which are vital to the Royal British Navy’s layered anti-submarine warfare (ASW) strategy. The Wildcat helicopter, based at RNAS Yeovilton, is equipped with cutting-edge radar and electro-optical sensors, providing rapid maritime reconnaissance and target tracking. The Merlin Mk2 helicopter, operated from RNAS Culdrose, is a specialist submarine hunter, fitted with advanced dipping sonar, sonobuoys and magnetic anomaly detection gear, capable of locating even the quietest submarines below the surface.

These assets worked in tandem to track the RFN Novorossiysk, a modern Kilo-class diesel-electric attack submarine designed for coastal patrols and well known for its stealth in submerged operations. Accompanying it was the Goryn-class tug Yakov Grebelski, which provides logistical and navigational support to Russian naval units on extended missions. The choice to keep the submarine surfaced through these busy sea lanes was not incidental; it sends a visible message and tests how NATO forces respond to assertive Russian movements so close to allied shores.

The need for such persistent surveillance comes amid a clear uptick in Russian naval deployments in the North Sea and around UK waters. Army Recognition has already reported on this increasing trend, including last month’s passage of the RFN Admiral Grigorovich, a guided-missile frigate known for its Kalibr cruise missiles, and the RFN Boikiy, a Steregushchiy-class corvette designed for anti-submarine warfare and coastal defence. Together, these vessels represent a multi-layered offensive capability, blending stealthy submarines with surface ships capable of striking targets at long range. Their combined operations near UK waters demonstrate a willingness by Moscow to probe the edge of NATO’s defensive lines, an approach that tests response times, tactics and endurance.

In this latest case, the Royal British Navy’s powerful network of sensors and maritime patrol protocols allowed them to detect and trail the surfaced submarine from the North Sea into the English Channel. HMS Mersey’s crew maintained continuous visual and electronic tracking while the Wildcat and Merlin helicopters relayed real-time sonar and radar data to ensure that the Russian flotilla’s every movement was recorded. This detection and shadowing pattern echoes last week’s encounter when HMS Mersey, alongside Portsmouth-based ships HMS Duncan and HMS Trent, were dispatched to observe and monitor the Admiral Grigorovich frigate and Boikiy corvette operating near the UK coastline.

By surfacing the Novorossiysk during transit, Moscow may well be signalling an intention to remind the UK and NATO that Russian submarines can and will assert presence in waters that are vital to Europe’s energy flows and undersea infrastructure. Such calculated moves are part of a broader geopolitical message that Russia continues to challenge Western maritime dominance, particularly along NATO’s northern maritime flanks.

Strategically, these repeated incursions reinforce the need for a robust and flexible maritime surveillance posture. The North Sea and the English Channel are among the world’s busiest maritime corridors, vital not only for commercial shipping but also for critical undersea cables and energy pipelines. Any interference, intentional or accidental, could have serious security and economic consequences for the UK and its allies. This is precisely why the Royal British Navy’s high readiness and layered response capability, integrating offshore patrol ships, multi-role helicopters, and NATO cooperation, remains an essential line of defence.

These operations, now a near-weekly reality, underline the increasing operational burden placed on Royal British Navy personnel. Yet, as Lieutenant Commander Dan Wardle of HMS Mersey stated, safeguarding national maritime interests demands constant vigilance and professionalism, qualities that crews have demonstrated repeatedly under growing pressure. As HMS Mersey handed over monitoring duties to NATO allies once the Russian units exited UK waters, the mission showed that Britain’s maritime commitment extends well beyond its shores, anchoring NATO’s wider deterrence posture.

Britain’s readiness to counter these activities is also reflected in its ongoing increase in defence spending, set to reach 2.6% of GDP by 2027 and with plans to rise to 3% in the next parliamentary term. As the Royal British Navy remains on the front line of this contest for maritime influence, it sends a resolute message to both allies and adversaries: the UK will not compromise on the integrity of its sovereign waters and will continue to uphold the security of the North Sea and the wider North Atlantic in partnership with NATO.