Nations are beginning to acquire a fleet of unmanned aerial vehicles, and about a dozen, led by the United States and Russia, are arming them. America first began deploying remotely piloted armed drones – starting with the infamous “Predator” drone –  during the Iraq War in 2004.  It’s used them ever since to launch lethal missile strikes on suspected terrorist holdouts.  Russia has recently injected armed drones into Ukraine, prompting a possible – and highly controversial – US response.  Other nations with armed drones include Israel, Iran, India and Pakistan  In addition, a growing number of non-state actors – for example, the Jalisco drug cartel in Mexico and Boko Haram in Nigeria, have begun deploying armed drones, primarily to defend their turf from incursions.

But there’s another kind of armed drone that hasn’t received much attention: Maritime drones.  While these surface and underwater drones are not yet proliferating at the rapid pace of aerial drones, a few countries, led by the United States, are increasingly looking seaward as part of their overall drone development.

Maritime drones, dubbed Underwater Unmanned Vehicles, or UUVs, aren’t necessarily deployed below the surface, though the few countries currently developing them tend to emphasize this role.  The Navy sees maritime drones as a key part of its Third Offset strategy, which focuses on a wide array of next-generation war-fighting technologies.  According to a 2016 DoD report entitled “Autonomous Undersea Vehicle Requirement for 2025,” UUVs are meant to supplement the capacities of America’s submarine fleet by conducting mine countermeasures or serving as decoys – missions considered too risky or time-consuming for manned vehicles.

Like aerial drones, maritime drones can function autonomously in some roles.  As far back as 2016, the Navy conducted an exercise in which a large group of autonomous surface vessels, or USVs, collectively patrolled a harbor.  Other Navy drone ships are  being programmed to track both surface craft and submarines. The Echo Voyager, the Navy’s UUV flagship, which was first introduced in 2016 and can operate autonomously for a full six months, is programmed to send data to its remote “captain” via satellite.  Now, the Navy plans to build a fleet of much larger USVs, in part to keep up with major powers like Russia and Great Britain.

To date, just one non-state fighting organization has joined the rapidly accelerating UUV/USV arms race.  In January 2017, Houthi rebels in Yemen used maritime drones to attack a Saudi frigate.  Pentagon officials were stunned because the attack  resembled a classic suicide bombing but in notable shift, there was no evident martyrdom involved.  Moreover, the rebels had no known ability to produce such a sophisticated USV themselves.  While not able to confirm the weapon’s origin, officials strongly suspected Iran, one of the non-Western nations with a dedicated drone development program.

The Yemen attack on the high seas has Pentagon officials increasingly worried about future attempts by terrorists to choke off or disrupt commercial sea traffic in the Straits of Hormuz and Mandeb, long considered vital shipping lanes for oil and other commodities. But US forces are prepared to defend against missile attacks on commercial vessels by manned aircraft or ships, not less detectable drone attacks carried out by their proxies. And the prospects of nuclear-armed UUVs bypassing Western radar altogether has begun giving Pentagon officials nightmares.

In the short term, defense analysts say the “dronification” of maritime warfare is likely to focus on the South China Sea, owing to its geo-strategic location as well as features that favor UUVs.  The US, China, Russia and the UK are all expanding their maritime drone presence there – the UK for the first time.  The Pentagon just added a large UUV dubbed Orca, which is poised to conduct anti-surface warfare, electronic airfare and strike missions.  But according to a January 2022 article in Asia Times,  owing to the uncharted nature of the region’s waters, many drones are also being tasked with “bathymetric mapping,” which includes “recording the thermal, magnetic, and acoustic properties of specific underwater passages to find blind spots where submarines can travel undetected safely.”  Without a better underwater blueprint, submarines operating in the South China Sea will continue to encounter a host of environmental obstacles that make their missions perilous, defense experts say.

For now, each nation’s drone development in the region will likely proceed without international incident.  But with the US and Beijing each expanding their naval presence, and with loud mutual saber-rattling over contested South China island territories an increasingly common feature of their bilateral relationship, experts say it’s only a matter of time before the two countries’ increasingly sophisticated UUVs and USVs become a flashpoint of open conflict.