In March 2024, scientists with China’s Northwestern Polytechnical University published an article in the peer-reviewed journal Ships and Offshore Structures with the relatively benign title, “Numerical investigation for the blockade capability of the multi-BWBUG cooperative system.” In addition to analyzing self-organizing underwater mesh networks of blended wing body underwater gliders (BWBUGs), the article explores the potential for pods of BWBUGS to fulfill a combat role by striking targets lying on the seabed. The article features an illustration that, at first glance, appears to depict a strike package of stealth bombers flying low over rugged terrain. Except the craft aren’t stealth bombers—they’re BWBUGs. And the terrain isn’t rolling countryside—it’s the ocean floor.

Discussions of seabed warfare are usually centered around attacks on critical underwater infrastructure (CUI)—power and telecommunications cables, oil and gas pipelines. But while these nodes in the global information and energy grids are indeed critical, they represent just one target set within a rapidly evolving undersea domain. Seabed warfare will increasingly be defined by the need to contest a dense battlespace teeming with sensor networks, communications nodes, autonomous vehicle hubs, and energy systems, with a range of commercial, scientific, and military assets, potentially finding themselves on a subsea strike target list. A 2023 Hudson Institute report, “Fighting Into the Bastions: Getting Noisier to Sustain the U.S. Advantage,” goes so far as to frame the coming battle for undersea supremacy as an analog to World War II and Cold War air operations. “Improved adversary defenses could degrade or defeat US undersea operations, preventing U.S. submarines from conducting critical missions such as sinking a Chinese invasion fleet or tracking Russian ballistic missile submarines (SSBNs),” writes Bryan Clark and Timothy A. Walton, Senior Fellows at the Hudson Institute’s Center for Defense Concepts and Technology. “To sustain its offensive undersea advantage, the U.S. Navy will need to take some lessons from air warfare and begin supporting submarines with systems designed to suppress or destroy enemy undersea defenses.”

Assets and Defenses in Seabed Warfare

Fixed Sensor Networks: Designed for surveillance of chokepoints, EEZs, and even open ocean transits, these sensitive arrays provide persistent monitoring of surface and subsurface operations. Severing, spoofing, or jamming them would create blind spots in situational awareness.

Energy and Docking Stations: Enabling long-duration, in-situ deployment of UUVs and other autonomous undersea systems, these might include UUV docking systems, like the U.S. Navy’s Forward Deployed Energy and Communications Outpost (FDECO) concept, or resident energy sources, like Teledyne Marine’s Subsea Supercharger, as well as tidal, thermal, or cabled recharging stations.

Communication Relays: Subsea acoustic relays, optical links, and data transfer nodes will be critical for enabling distributed underwater operations, and for linking undersea platforms to surface, air, or space-based assets.

Position, Navigation, Timing (PNT) Infrastructure: Recalibration nodes for submerged vehicles operating beyond GPS coverage, as well as LBL beacons for local or regional UUV deployments, will be essential to ongoing underwater operations. Disabling or spoofing them could misdirect assets, increasing risk of mission failure.

Modular Launch Systems: Payload modules containing unmanned vehicles, sensors, or effectors could be prepositioned during peacetime for remote activation in the event of armed conflict. Destroying them preemptively would remove this latent capability before it can be brought to bear.

Advanced Systems for Subsea Strikes

Subsea strikes will require platforms capable of precision localization, maneuverability, and autonomous delivery of kinetic or non-kinetic effects using pre-programmed or remotely updated targeting. Several such systems are approaching maturity and may be ready for deployment in the near future:

The Anduril Industries Copperhead is a “high speed underwater munition” hybrid UUV/torpedo, available in two variants—a 21-inch diameter vehicle, analogous to the U.S. Navy’s Mk-48 heavyweight torpedo, and the Copperhead-M, a 12.75 inch diameter vehicle, analogous to the U.S. Navy’s Mk-54 lightweight anti-submarine warfare (ASW) torpedo.

The Leidos Sea Dart, a low-cost AUV optimized for ISR and ASW roles, could be weaponized to attack seabed targets. Its 19-hour endurance and depth rating of 600 meters (1968 feet) would enable standoff deployment against a wide range of undersea infrastructure. The Sea Dart is currently available in 6 and 9 inch (152 and 226 mm) diameters, with a 12.75 inch (323 mm) under consideration.

The RTX Barracuda, a tethered, semi-autonomous mine neutralizing underwater vehicle could be repurposed as an offensive subsea strike weapon. Mine countermeasures (MCM) is essentially a defensive operation for striking seabed kinetic effectors emplaced by adversaries to shape or deny the maritime battlespace. Deployed from a canister launcher aboard an unmanned surface vehicle (USV), the Barracuda could conceivably be reengineered with increased pressure tolerance and a longer tether, or untethered acoustic communications for autonomous operations, to strike deeper seabed targets.

The Areté REMORA, developed under a Navy SBIR/STTR contract, is a scalable, hydrodynamic payload delivery system that allows expendable payloads to be externally deployed from virtually any UUV. The REMORA module attaches to the vehicle’s hull using a high-strength vacuum force, and is self-deployed by the host vehicle using a high-frequency, through-hull acoustic signal. A BWBUG such as Northrop Grumman’s Manta Ray could carry multiple REMORAs in order to deploy clusters of kinetic effectors against seabed targets.

Subsea strike would not require a target’s complete or even near destruction to achieve operational or strategic effects. Minor damage, such as throttled power throughput, a degraded hydrophone array, or a compromised pressure housing could achieve mission kills like localized ISR blackouts, severed C2 comms, drained batteries, or the suppression of prepositioned effectors. Moreover, repair or replacement of damaged systems would require specialized vessels, ROVs, and trained crews operating in challenging conditions. Adversaries may lack the capacity, or an uncontested environment, to respond, turning a minor subsea strike into a long-term disruption.

Just as air warfare evolved to target logistics hubs, radar arrays, communication nodes, and munitions depots, subsea and seabed warfare (SSW) will see states and non-state actors target not only CUI, but the full range of systems and infrastructure populating the underwater battlespace. At the operational level of war, subsea strike will be essential for enabling freedom of maneuver for crewed submarines and other high-value undersea platforms. But it will also offer a means to project power and impose costs without crossing the threshold of open conflict, all while avoiding detection or attribution, making it a strategic force multiplier as well.