In our first three articles, we examined how USVs extend maritime intelligence through ISR and SIGINT, how they strengthen Maritime Situational Awareness (MSA) and the Common Operational Picture (COP), and how they protect Critical Undersea Infrastructure (CUI). Recent incidents in Denmark—where airports were disrupted by suspected drone launches from nearby vessels—have shown that hybrid threats are evolving. This article explores how USVs can shadow suspect vessels throughout their passage in Danish waters and monitor for both airborne and subsurface drone activity. Shadowing Vessels in Transit Suspect vessels, including sanctioned tankers, intelligence-gathering “research” ships, or bulk carriers with opaque ownership, routinely pass through narrow straits such as Øresund and Storebælt. Operating under “innocent passage,” they cannot easily be intercepted, but their activities must be monitored. USVs provide a persistent and discreet shadowing capability: – Full route coverage from Skagen to Bornholm (≈250–377 nm). – Safe standoff distance while maintaining continuous tracking. – Autonomous maneuvering to mirror course and speed changes. – No crew exposed to risk. Multi-Domain Sensor Suite Surface Awareness – EO/IR cameras for 24/7 visual and thermal documentation. – Marine radar and AIS receivers to track vessels, even “dark ships.” Airspace Monitoring – Compact counter-UAV radar for small drone detection. – RF scanners to capture control/telemetry signals. – IR/optical sensors to identify drone launch events. Underwater Surveillance – Hull-mounted or towed sonar to detect UUVs, divers, or anomalies near subsea cables. – Passive hydrophones to capture acoustic signatures of underwater activity. *By combining these layers, USVs close surveillance gaps across all domains: surface, air, and subsea.* Operational Use Case Scenario: A sanctioned bulk carrier approaches Danish waters, suspected of preparing drone operations. 1. Deployment: A ProZero USV launches ahead of the target. 2. Shadowing: Maintains safe offset, logging AIS behavior and unusual deck activity. 3. Air Monitoring: Detects and records UAV launches with radar, RF, and EO/IR sensors. 4. Subsea Scanning: Sonar sweeps reveal any underwater deployments. 5. Real-Time Relay: All data streams to command centers, enhancing the COP and enabling rapid response. Advantages of USV Shadowing – Persistent Coverage: 24/7 surveillance across entire transit routes. – Reduced Risk: No crew in harm’s way. – Multi-Domain Awareness: Integrated monitoring of surface, air, and subsurface. – Scalability: Deploy multiple USVs to cover larger areas or several vessels. – Interoperability: Seamless integration with naval, coast guard, and allied COP systems. Conclusion Hybrid threats at sea are real, immediate, and disruptive. Recent events highlight the need to detect and document suspicious activity—whether airborne, surface-based, or underwater. By deploying ProZero USVs, authorities gain a force multiplier: autonomous platforms capable of shadowing suspect vessels, identifying drone launches, and delivering actionable intelligence without risking personnel. USVs are now an indispensable tool for safeguarding maritime security against hybrid threats in the world’s busiest and most vulnerable waters.

Critical Undersea Infrastructure (CUI)—including subsea pipelines, fibre-optic communication cables, and offshore energy platforms forms the lifelines of modern economies and security frameworks. These assets are increasingly vulnerable to accidental damage, criminal interference, and hybrid threats. The strategic importance of CUI has never been greater, and Unmanned Surface Vessels (USVs) are emerging as key tools in protecting it.  Persistent Patrols and Monitoring  USVs can be deployed to patrol fixed routes above critical infrastructure, operating as autonomous sentinels. Equipped with downward-looking sonar, subsea sensors, and video surveillance, they can detect anomalies such as physical disturbances on the seabed, unauthorised diving activity, or unidentified underwater vehicles. By maintaining 24/7 coverage without fatigue, USVs close a long-standing surveillance gap.  Their ability to remain on station for extended periods means that any suspicious activity can be detected early, assessed in real time, and responded to quickly. This is vital for deterring sabotage or hostile acts before damage is done.  Rapid Incident Response and Damage Assessment  In the event of an incident—whether an equipment failure, anchor strike, or deliberate attack—speed matters. Pre-positioned USVs can be redeployed immediately to the affected area, transmitting live data, imagery, and sonar readings back to command centres. This rapid situational understanding enables faster repair mobilisation and better evidence gathering.  Deterrence Through Visible Presence  Just as manned patrols deter unlawful activity, the constant presence of USVs above or near CUI sends a clear signal that these assets are under watch. This presence complicates planning for any potential adversary and increases the perceived risk of detection.  USVs in Multi-Domain Operations (MDO)  The protection of CUI does not happen in isolation—it is part of broader Multi-Domain Operations (MDO). USVs integrate with unmanned underwater vehicles for subsurface inspection, unmanned aerial vehicles for overhead monitoring, and manned naval units for interdiction or repair support.   In an MDO context, USVs act as surface-based hubs, relaying information between domains and providing a real-time operational link from seabed to maritime operation centers. This integration is aligned with NATO’s vision of a connected “digital ocean,” where layered sensors and platforms across domains share data seamlessly to enable faster, coordinated responses.  Strategic Relevance for NATO and Allies  NATO’s focus on safeguarding undersea infrastructure recognises its strategic and economic importance. The establishment of dedicated centres for CUI security and exercises simulating infrastructure attacks highlight the urgency of this mission. USVs, with their persistence, adaptability, and interoperability, are central to delivering the constant vigilance required.  Conclusion  USVs are redefining how nations protect their most vital maritime assets. By providing persistent patrols, rapid response capability, and seamless integration into multi-domain operations, they deliver both deterrence and defence against an evolving set of threats to CUI.  As the maritime security environment grows more complex, the role of USVs will expand—offering nations and alliances like NATO a critical edge in resilience, readiness, and operational reach.  → To learn more about how USVs can enhance the protection of your critical undersea infrastructure, contact us at Tuco Marine / ProZero Workboats.  Tuco Marine has extensive experience in designing USVs, and our vessels have been operating 24/7, year-round, in Danish waters for many years – including the North Sea, where challenging wave and wind conditions put both design and performance to the test. 

Maritime Situational Awareness (MSA) is the foundation of maritime security and operational effectiveness. Without accurate, timely information, even the most capable naval force risks making decisions in the dark. Unmanned Surface Vessels (USVs) are revolutionising MSA by acting as persistent, intelligent, and interoperable assets that strengthen the Common Operational Picture (COP) and enable seamless collaboration across domains.  From Local View to Common Operational Picture (COP)  A COP is a unified, real-time visualisation of the maritime environment, compiled from multiple sources: surface, subsurface, aerial, and space-based sensors. USVs enhance the COP by supplying continuous, high-quality data streams from their advanced radar, EO/IR cameras, AIS receivers, sonar, and environmental monitoring systems.  This constant data feed ensures that the COP is both comprehensive and current. For example, USVs can operate beyond the range of shore-based radar to fill critical coverage gaps in EEZs, straits, or remote offshore regions. The result is a live, accurate picture of maritime activity that allows navies, coast guards, and allied partners to respond rapidly and in coordination.  USVs as Interoperable Maritime Autonomous Systems (MAS)  Modern naval strategy increasingly relies on Maritime Autonomous Systems (MAS)—integrated networks of unmanned and manned platforms working together. Within this framework, USVs often collaborate with:  – Unmanned Underwater Vehicles (UUVs) to monitor subsurface threats and infrastructure  – Unmanned Aerial Vehicles (UAVs) to extend sensor coverage and provide rapid overwatch  – Manned vessels and aircraft to conduct intercepts, boarding operations, or other high-value missions  By linking USVs into MAS, commanders gain layered surveillance from seabed to airspace. A USV can detect an unknown contact, cue a UAV to investigate from above, and share findings instantly with both a nearby frigate and a shore-based maritime operation center.  Operational Advantages of USV-Enhanced MSA  Persistent Coverage: Long-endurance USVs can patrol designated sectors for days or weeks without downtime. Scalable Deployment: Fleets of USVs can be rapidly deployed to expand surveillance or focus on a specific hotspot. Risk Reduction: Operating unmanned platforms in contested waters reduces exposure for human crews. Real-Time Intelligence: Continuous data feeds shorten the decision-making loop from detection to action. Allied Interoperability: Standardised data formats and communications protocols enable integration into NATO and coalition COP systems. Beyond Surveillance – Data Fusion and Decision Superiority  The power of USVs in MSA is not just in collecting data, but in contributing to advanced data fusion. When USV sensor inputs are combined with satellite imagery, coastal radar, and other unmanned platforms, they help eliminate blind spots and reduce false positives. This gives commanders the confidence to act decisively.  For NATO and allied forces, the integration of USVs into the COP supports joint operations, shared situational awareness, and faster, coordinated responses to emerging threats—from illegal fishing fleets to grey-zone incursions.  Conclusion  USVs are more than just sensors at sea; they are integral to a connected, multi-domain surveillance network. By enhancing MSA, enriching the COP, and integrating seamlessly into MAS, they multiply the effectiveness and reach of modern maritime forces.  → Interested in exploring how USVs can strengthen your maritime situational awareness?  Contact us at Tuco Marine / ProZero Workboats to learn more about our operationally proven USV platforms.  Tuco Marine has extensive experience in designing USVs, and our vessels have been operating 24/7, year-round, in Danish waters for many years – including the North Sea, where challenging wave and wind conditions put both design and performance to the test. 

As maritime security challenges intensify—from grey zone incursions to hybrid threats—Unmanned Surface Vessels (USVs) are emerging as essential assets for modern naval and coast guard operations. These autonomous or remotely operated platforms are more than tools for data collection—they’re strategic enablers of persistent intelligence, enhanced surveillance, and real-time decision-making.  In this first article of a three-part series on the role of USVs in sovereignty enforcement, we explore how these vessels are redefining Intelligence, Surveillance, and Reconnaissance (ISR) and Signals Intelligence (SIGINT) in the maritime domain.  Persistent ISR at Sea: Coverage Without Compromise  Traditional ISR at sea relies on a mix of manned patrol vessels, maritime patrol aircraft, coastal radar, and satellites. Each of these has strengths—but also critical limitations. Patrol vessels are resource-intensive. Aircraft have limited endurance. Satellites offer snapshots, not persistence.    USVs offer a new paradigm:  – Persistent presence without fatigue  – Autonomous or semi-autonomous operation  – Low cost per operating hour  – Rapid redeployability  Outfitted with radar, EO/IR sensors, AIS receivers, and even sonar, USVs can maintain long-duration patrols in EEZs, chokepoints, or sensitive maritime zones. They can track vessel movements, monitor environmental conditions, record deviations from standard traffic patterns and shadow targets of special interest.    USVs can also operate in swarms or organized naval groups/forces, covering vast areas without gaps. This makes them ideal for:  – Monitoring grey-zone actors or illegal fishing fleets  – Patrolling offshore wind farms, pipelines, and other critical assets  – Supporting maritime embargo enforcement or counter-smuggling operations  Critically, ISR-enabled USVs can act as early-warning platforms, feeding data to operations centers in real time—offering the maritime equivalent of an unmanned picket line.  Signals Intelligence (SIGINT): Quiet Listening, Strategic Advantage  SIGINT is a vital layer of maritime situational awareness—and an area where USVs excel. By carrying tailored payloads, USVs can collect:  – Communications intelligence (COMINT) — intercepting VHF/UHF/and maritime comms, as well as satcom or GSM-intercept where applicable.  – Electronic intelligence (ELINT) — detecting emissions from radar or jammers  – Emitter geolocation — triangulating signal sources for threat attribution  Unlike manned vessels, USVs can loiter discreetly in sensitive areas for extended periods, silently gathering intelligence. This makes them ideally suited for:  – Detecting unauthorized communications near protected zones  – Mapping the electromagnetic order of battle in disputed waters  – Conducting electronic surveillance near maritime boundaries  For NATO-aligned navies and maritime agencies, SIGINT-enabled USVs can provide critical insight into adversary behavior patterns and electronic posture—without risking personnel or high-value platforms.  Human-in-the-Loop Control, AI on the Horizon  Today, most USVs conducting ISR/SIGINT are remotely operated, with skilled crews overseeing missions from onshore command centers. This ensures real-time interpretation and response, which is critical in high-stakes environments.    However, as machine learning advances, we’re seeing a shift toward onboard AI-powered signal analysis, anomaly detection, and adaptive mission planning. This evolution will allow future USVs to:  – Prioritize targets dynamically based on signal profiles  – Adjust patrol routes autonomously to maintain coverage  – Pre-filter intelligence for human analysts—reducing workload and reaction time  In short, USVs are not only extending the reach of maritime surveillance but are on track to amplify the intelligence yield per deployed asset.    Strategic Implications for Sovereignty Enforcement  In contested waters, situational control often depends on who sees and understands first. ISR and SIGINT-capable USVs tilt this equation in favor of the defender by:  – Denying operational space to unauthorized actors  – Maintaining persistent awareness of maritime activity  – Providing a non-escalatory but credible surveillance posture  For nations facing grey zone pressure or asymmetric threats at sea, USVs provide a scalable, resilient, and cost-effective force multiplier—one that supports both national security objectives and allied interoperability.  Closing Thoughts  Unmanned Surface Vessels are not a future capability—they are operational now, quietly transforming the intelligence landscape at sea. By pairing persistent ISR with discreet SIGINT, they deliver unmatched value in sovereignty enforcement, early warning, and maritime domain awareness and constitutes an invaluable support to traditional maritime surveillance and sovereignty enforcement with manned naval vessels.  → Want to learn how USVs can support your maritime intelligence and surveillance needs?  Tuco Marine has extensive experience in designing USVs, and our vessels have been operating 24/7, year-round, in Danish waters for many years – including the North Sea, where challenging wave and wind conditions put both design and performance to the test.  Contact Tuco Marine / ProZero Workboats to learn how our USVs can give you a real operational advantage.