The Pentagon is soliciting designs for low-cost autonomous drone boats to enhance maritime expeditionary capabilities in response to successes and strategic considerations highlighted by operations in conflict zones like the Ukraine war.
This month, The Warzone reported that the Pentagon is seeking proposals for the Production-Ready, Inexpensive, Maritime Expeditionary (PRIME) Small Unmanned Surface Vehicle (SUSV) project, which aims to create fleets of low-cost, highly autonomous drone boats capable of chasing down and attacking non-cooperative ships.
The Warzone says that the Defense Innovation Unit (DIU) has called for designs capable of traveling between 500 and 1,000 nautical miles in moderate sea states, with a total payload of 1,000 pounds and a sprint speed of at least 35 knots. The designs will also have autonomous navigation and must be capable of performing tasks even in GPS-denied environments.
The PRIME project also requires vendors to demonstrate a diversified and resilient manufacturing supply chain for critical components, including automatic emissions control, tethered aerial drones, diversified, redundant and adaptive communications, and automated contact recognition.
It mentions that the project’s tertiary attributes include accepting various modular payloads, sensors and effectors, collaborative autonomy and the ability to de-conflict with proximate drones. In addition, the PRIME project aims to enhance the capabilities of foreign allies and partners, particularly in the context of a potential conflict in the Taiwan Strait.
The Ukraine war may have given impetus for the development of such systems. Despite Ukraine effectively lacking a navy, its unmanned surface vehicles (USV) have inflicted severe losses on the Russian Black Sea fleet.
This month, Ukrainian military intelligence released a video showing a successful kamikaze USV strike on the Russian Tarantul-II-class missile corvette Ivanovets. The video shows multiple USVs approaching the ship from different directions.
While the ship performed evasive maneuvers and attempted to destroy the USVs, its efforts were in vain, as seen in the catastrophic explosion that sunk it.
Ukrainian military intelligence also released a video showing another successful USV strike last August on the Russian Ropucha-class landing ship Olengorsky Gornak. A subsequent video shows the Olengorsky Gornak heavily listing portside while being towed back to port.
Earlier, the Ukrainian Ministry of Defense (MOD) released a video last May showing a USV attack on the Russian Yuri Ivanov-class intelligence ship Ivan Khurs. However, whether the Ivan Khurs was sunk, damaged or unscathed in the attack’s aftermath is unclear.
Even non-state actors have embraced using USVs to attack warships. Last month, Business Insider reported that Houthi rebels attempted a USV attack from Yemen but it was unclear what its target was. Business Insider reported that the USV transited about 15 miles into international shipping lanes before detonating, causing no damage.
Overmatched navies like the Taiwanese Navy or cash-strapped ones like the Philippine Navy may also consider developing USVs to build asymmetric warfare capabilities.
In a January 2023 article for RAND, Scott Savitz says that Taiwan could launch hundreds or even thousands of USVs to repel a Chinese invasion fleet from multiple piers and small islands under its control.
Savitz notes that swarming USVs can overwhelm the defenses of People’s Liberation Army-Navy (PLA-N) warships while PLA-N troop transports and cargo ships may have limited USV defenses.
He mentions that if each USV costs US$250,000, per Ukrainian estimates, Taiwan could buy 1,000 for just 1% of its US$20 billion annual defense expenditure, with low fuel, maintenance and training costs.
He also says Taiwan’s technological acumen means it could design and build thousands of these weapons over a few years. However, Savitz notes that USVs alone cannot counter an invasion fleet but should be used with naval mines, anti-ship missiles and other weapons.
Those cases illustrate the difficulty of defending against swarming USVs and that the technology can be an enabler for asymmetric naval warfare.
USV swarms can overwhelm a target ship’s defensive systems by sheer numbers, ensuring that at least some of the attacking drones will hit their targets.
Some USV designs have a low profile close to the water’s surface, which masks them from enemy shipboard sensors and allows them to get up close to their target.
Improvements in artificial intelligence allow USVs to perform complex maneuvers, increasing the unpredictability of an attack. Their cost-effectiveness allows resource-strapped navies to produce relatively large numbers of USVs to impose significant costs on a better-resourced opponent.
USVs may also have significant psychological effects on a superior adversary, as they can shatter overconfidence and a false sense of security, leading to the withdrawal of naval forces and misallocation of resources to defend against such attacks.
However, USVs may not be the naval “wonder weapon” some believe. In a February 2023 article for the Bulletin of Atomic Scientists, Jonathan Panter and Johnathan Falcone point out the limits of the technology.
Panter and Falcone mention that wind, waves and seawater quickly degrade engineering systems at sea, and as USVs get more complex without any human aboard to do repairs, they are more likely to fail. They also point out that the more autonomous USVs become, the more tempting they become as cyber-targets.
According to Panter and Falcone, while USVs use pre-existing image recognition software for target identification and don’t require GPS for short-distance travel to attack stationary targets, Ukraine’s USVs still have a visible external antenna to enable human control via a high-frequency communications link or satellite.
They note that external communication links are a cyber-attack vector, saying that while encryption provides substantial protection, failure to load cryptographic keys can interrupt communications and that encryption keys can be compromised if the USV is captured.
They mention Russia’s improving ability to jam data links and anti-satellite weapons, noting that any technological advantage afforded by the US Starlink satellite constellation to Ukraine’s USVs may be short-lived.
They also point out the supply chain vulnerabilities for USVs, stating that no state produces the advanced microchips required for autonomous systems except for Taiwan and Israel. That, in turn, enables vulnerabilities to be etched on the most critical chips used in USVs, potentially making them immune to any software patch.
Given that, Panter and Falcone caution that while the US rushes to field USVs, the hype should not detract policymakers and operators from significant use-case and cybersecurity limitations.