Sesimbra, Portugal, on a clear September morning, Europe’s attention is trained on the sea floor as a fleet of unmanned systems demonstrates its evolving mine countermeasures capability. A six-and-a-half meter autonomous underwater vehicle, nicknamed Greyshark, glides just beneath the surface near a Portuguese Navy vessel, its silhouette softened by the Atlantic light. The drill, part of NATO’s Dynamic Messenger and REPMUS exercises, gathered more than 200 unmanned platforms to examine how crews coordinate machines, not just humans, in dangerous waters. The objective is simple in wording but complex in execution: detect, classify, and neutralize moored or drifting mines while keeping divers out of harm’s way.

These exercises show that undersea drones are stepping into a broader role in naval warfare. The Greyshark, equipped with four high‑resolution sonars, LIDAR scanners, electromagnetic detection, and two cameras, can operate at ranges up to 8,000 nautical miles, enabling long‑range reconnaissance and multi‑step mine‑hunting campaigns. Germany also showcased EvoLogics’ Sonobot surface gateway and the Quadroin AUV, the underwater variant used in swarms. The Sonobot provides underwater positioning and data networks — wifi and GPS underwater — for other autonomous systems, while the Quadroin coordinates multiple units at once to sweep the seabed and capture video of potential mines. Together, these tools illustrate how a connected fleet can reach into areas previously accessible only by manned divers.

From manual to machine

During REPMUS, exercise controllers steadily increased task difficulty. Divers initially knew the zone but were later confronted with last-minute briefs and tighter time constraints, testing not just the drones but the human teams that command them. The French Navy fielded Exail’s A9‑M autonomous underwater vehicle to survey the seabed, evaluate sonar data onshore, and confirm potential mines with divers or remotely operated vehicles. Louis, an EOD officer describing future steps, says the plan is to push toward greater AI integration so drones can autonomously classify detections, reducing the time from detection to decision.

Operational lessons and hiccups

The field also highlights the friction that accompanies rapid tech adoption. The British Navy relied on the REMUS 100 AUV for joint exercises with the U.S. and Dutch forces, but operators reported overheating during peak heat and had to improvise cooling with blankets and earlier launches. In another episode, two German Sonobots collided during a demonstration. A Portuguese fishing boat briefly cut into the exercise area and damaged the French A-9M drone, forcing its withdrawal from the demo. While these incidents underscore growing pains, they also reveal a practical truth: robust unmanned operations demand resilient platforms, smarter data links, and clearer rules of engagement.

Policy and future outlook

Europe is moving to codify how unmanned systems integrate into mine warfare, including data-sharing protocols, command-and-control architecture, and safety standards for mixed fleets. AI could be the next leap, allowing drones to autonomously classify threats from sonar returns and leaving operators to focus on verification and decision-making. The broader implication is clear: as undersea drones become more capable, defense planners must rethink training, maintenance, and shipboard integration to realize the full promise of swarms and gateways.

For defense planners, the message was unmistakable: the era of isolated, manual mine hunting is giving way to networked, automated operations that can extend reach and reduce risk. The lessons learned here will feed into European procurement, alliance interoperability, and future NATO exercises as fleets increasingly rely on unmanned assistants for the underwater battlespace.

Conclusion

European navies are turning to undersea drones to redefine mine countermeasures and protect critical underwater infrastructure. The tests underscore not only advanced sensors and multi‑vehicle coordination but also the strategic shift toward AI‑assisted autonomy and interoperable networks. As these systems mature, they will reshape how fleets hunt mines, protect assets, and train crews for the next generation of undersea warfare.