Naval drones could reshape sea warfare in many of the same ways aerial drones have reshaped land and air warfare—but the maritime domain comes with far more serious challenges.

While aerial drones in the wars in Ukraine and the Persian Gulf dominate world headlines, the US Navy is quietly investing billions into a parallel revolution. “Unmanned Undersea Vehicles,” (UUVs), or underwater naval drones, are becoming central to how the US Navy—outgunned by China’s People’s Liberation Army Navy in both ship hulls and raw industrial might—intends to compete with Beijing’s rapidly expanding maritime forces.

Just as drones are slated to transform air warfare, the Pentagon expects autonomous systems to fundamentally reshape undersea warfare. One day soon, the Navy could conduct dangerous operations, like surveillance, mine warfare, and strikes, without risking sailors aboard crewed submarines.

The US Navy’s Three-Tier Underwater Drone Fleet

The Navy is working on three tiers of underwater drone.

The first tier is Extra-Large UUVs (XLUUVs), which are essentially unmanned robotic submarines. Boeing’s Orca XLUUV, for example, is an 85-ton autonomous submarine with diesel-electric propulsion, lithium-ion batteries, a nautical range of 6,500 nautical miles (7,480 miles), and a 34-foot payload bay. The Orca can conduct minelaying missions, electronic warfare, smaller drone deployment, and operating inside heavily defended waters. The Manta Ray drone, now under development by DARPA, is a more experimental concept focused on extreme endurance that can reportedly hibernate on the seafloor for extended periods while consuming minimal energy.

The second tier involves tactical scouts—drones that act as “loyal wingmen” for submarines and surface ships, much as the Collaborative Combat Aircraft aerial drones do for the US Air Force’s fighter jets. Key systems include the Lionfish, REMUS 600, and Knifefish. The mission set for these tactical scouts includes mine hunting, environmental mapping, reconnaissance, and oceanographic intelligence gathering. Before sending exquisite warships into dangerous waters, commanders can send drones first, reducing risk and improving situational awareness. 

The third, and potentially most important, tier is small drones—basically expendable underwater scouts. Examples of these include the REMUS 100, Mk 18 Swordfish, and Teledyne Gavia. Up until now, these models have often been deployed by SEAL teams, EOD units, and special operations forces. Typical uses include harbor security, beach reconnaissance, and mine clearance. Operating with a similar logic to aerial drones, these small UUVs are cheap, portable, and replaceable—and the outcome of a future war is likely to come down to which side is able to mass-produce them in larger numbers and more cheaply than the other.

Drones Are Coming for Sea Warfare, Too

Historically, undersea warfare depended on a handful of very expensive, very hard to replace submarines. But in the future, large networks of autonomous sensors will spread throughout contested waterways—the Taiwan Strait, South China Sea, First Island Chain, and GIUK Gap, for instance—with a goal of creating persistent underwater awareness. In short, instead of hunting submarines individually, militaries may attempt to blanket entire regions with sensors. 

The Pentagon likes the math of UUVs. The Virginia-class submarine costs roughly $4 billion to build, while an Orca XLUUV with comparable functions costs only tens of millions of dollars. Strategically, this is appealing; a commander may be willing to risk an autonomous submarine in a place the Navy could never risk a Virginia-class boat and its crew. This reflects a broader trend, where military planners are increasingly attracted to affordable mass over a handful of sophisticated, concentrated platforms. 

Challenges remain, of course. The ocean makes networking between drones exceedingly difficult, far harder than it has been on the battlefield of eastern Ukraine. Radio signals do not travel effectively underwater, so drones are often forced to operate in isolation. Similarly, GPS cannot penetrate seawater, so navigation is complicated; UUVs are forced to rely on inertial navigation, Doppler velocity logs, and terrain mapping. These measures are imperfect, and navigation drift accumulates over long distances. Finally, long-duration underwater operations require enormous battery capacity—a problem for which no company has yet devised a cost-effective solution. 

Still, the trend line is clear. Autonomous systems could transform maritime chokepoints. An Orca could autonomously travel into a contested region and lay mines without exposing a crewed submarine.These systems could become critical tools for controlling access to key waterways.

About the Author: Harrison Kass

Harrison Kass is a writer and attorney focused on national security, technology, and political culture. His work has appeared in Tablet, City Journal, The Hill, The Spectator, and The Cipher Brief. He holds a JD from the University of Oregon and a master’s in Global & Joint Program Studies from NYU. More at harrisonkass.com.

The post The US Navy’s Underwater Drones: A Gamechanger for Sea Warfare? appeared first on The National Interest.

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