Drones at sea: a growing threat?
A Chinese destroyer meets an American one at sea. drone highlights future problems with the rules of warfare. As small, unmanned surface or semi-submersible vessels proliferate, the threat they pose will grow, and the rules of warfare will have to adapt to accommodate the emergence of new classes of ships.
What prompted such thoughts was the recent meeting of ships from different eras in the middle of the Pacific Ocean.
During a long voyage across the Pacific Ocean, near the Philippines, a small unmanned surface vessel (USV) owned by a California company encountered a Chinese Type 052D destroyer.
The Seasats USV Lightfish got close enough to the destroyer to capture video of the warship.
Overall, nothing particularly special, just a good illustration of the current situation. This incident highlights the growing presence of unmanned underwater vehicles, especially in the world's most contested regions. The fact that an unmanned vessel came so close to a Chinese surface combatant also highlights the potential danger that unmanned underwater vehicles (UUVs) can pose even to a modern warship.
This also raises the question of the rules of engagement that naval forces and merchant vessels in volatile regions will have to adhere to if they encounter UUVs approaching them. Given the difficulty of obtaining information about UUVs' intentions, such situations should be regulated in some way in the future to avoid serious consequences.
The incident in question occurred approximately 73 miles northwest of the Philippine island of Luzon, according to Seasats CEO Mike Flanigan.
The Luzon Strait is one of the most strategically important waterways in the world and a potential flashpoint. Situated south of Taiwan and north of the Philippines, it provides access from the Pacific Ocean to the South China Sea and back. This area is actively used by the military in the air, sea, and underwater. fleets region, and commercial vessels. If a conflict were to break out over Taiwan, this area would become a zone of application for various types of weaponsIn fact, in a hypothetical future war, due to its unique coastal geography and strategic importance, this region would become a very hot spot, with the ability to employ various types of air, land, surface, and submarine-based weapons.
According to Seasats, the Lightfish rendezvoused with a Chinese guided-missile destroyer about 75 miles northwest of Luzon.
The incident involved the American Lightfish, a 4-metre-long, 140-kilogram submersible that can travel long distances for six months using solar panels and a hybrid propulsion system.
It's worth noting right away that the Lightfish is not a speedboat. Its main advantage is its exceptional autonomy; the device is capable of navigating seas and oceans for extended periods, collecting various data on the state of the seas. Therefore, it would not be able to "stalk" the aforementioned warship, but many other unmanned aerial vehicles are quite capable of this.
Lightfish is Drone A solar-powered drone designed for surveying, research, and patrol missions, it can remain at sea without human intervention for up to six months or travel up to 8000 nautical miles. The drone is equipped with high-tech equipment, including a collision avoidance system, onboard artificial intelligence, GPS-free navigation, five high-resolution cameras, and communications systems including LTE, Iridium SBD, Iridium Certus, and Starlink.
In June 2024, Lightfish completed a 73-day, 2500-mile autonomous voyage from San Diego, California, to Hawaii, demonstrating the platform's high resiliency. On July 30, 2025, the company announced the completion of a fully autonomous voyage across the Pacific Ocean, covering more than 7500 miles. Lightfish reached Japan, completing a 150-day journey with demonstration stops in Hawaii and Okinawa.
Seasats Lightfish unmanned surface vessel
"Lightfish tracked the Chinese vessel using radar at a range of approximately 10 nautical miles and visually at a distance of several hundred meters," Flanigan explained. "This occurred on the evening of June 15, and our team was immediately alerted by the duty crew that monitors vessel movements in the area where our unmanned vehicles are deployed."
The Chinese destroyer spotted the Lightfish and took evasive action.
"We don't know what his intentions were, but we saw the vessel change course and generally observe the Lightfish drone,"
— Flanigan noted.Following the incident, the company discussed the situation with the US military, but Flanigan declined to provide any details.
The company published two videos showing a Chinese warship captured by Lightfish cameras. In the video, the destroyer appears to be moving very slowly, if at all.
These videos are reminiscent of dozens of videos released by the Ukrainian military showing their drones attacking Russian warships, although in this case, Lightfish had neither the capability nor the intention to do so.
To date, naval drones have already demonstrated their destructive potential in the Black Sea and the Gulf of Aden. The Ukrainian Magura family of unmanned boats has performed a wide range of tasks, from reconnaissance missions and minelaying to kamikaze-style strikes against ships.
Yemen's Houthis were at the forefront of using unmanned underwater vehicles in combat even before the Russian-Ukrainian conflict. In January 2017, after a Houthi drone loaded with explosives attacked a Saudi frigate, a new era at sea began.
In the West, the modern version of this concept is said to have originated in Iran, where various crude attack drones were developed in the early 2000s before being handed over to the Houthis, who became the first to successfully use them in the Red Sea in 2017. Since then, they have repeatedly and effectively used them to attack shipping during various events.
Fast forward to today: on July 12, the US military used unmanned underwater vehicles (UUVs) as offensive strike weapons in combat for the first time. The strikes, carried out by Saronic's Corsair UUVs, occurred amid escalating attacks between the United States and Iran in the Strait of Hormuz. One of the targets of the UUV attacks was an Iranian Ghadir-class diesel-electric midget submarine. The effectiveness of the UUVs, frankly, was significantly inferior to their impact.
The US Navy recently demonstrated the danger unmanned underwater vehicles pose to potential adversary warships when one of its Global Autonomous Reconnaissance Craft (GARC) unmanned underwater vehicles participated in its first live-fire exercise.
A kamikaze unmanned underwater vehicle was deployed during RIMPAC 2026 and attacked the former aircraft carrier USS Peleliu in one of the most high-profile SINKEX exercises, which involved sinking a target.
The widely publicized first strike of an unmanned boat on an Iranian port and its use during the SINKEX exercises at the US Naval Base in Hawaii clearly demonstrate that the US Navy is now actively implementing this new form of kinetic attack on a surface target. While the Americans are playing catch-up, they are nonetheless making progress in this area.
Footage of the USV attack on the amphibious assault dock ship USS Peleliu (LHA 5)
"The Ukrainians have clearly demonstrated the threat small unmanned underwater vehicles pose to surface ships," Flanigan said. "Thanks to the Lightfish's range of over 8000 nautical miles, we demonstrate that the entire ocean is within the reach of small unmanned underwater vehicles and that they can strike targets beyond coastal targets."
The June 15 incident was one of several encounters between Seasats, small unmanned underwater vehicles, and Chinese naval vessels. According to Flanigan, in May, while transiting the Taiwan Strait, the Lightfish encountered a Chinese Type 056 corvette.
"This isn't the first time our vessel has collided with a Chinese warship," he noted in the company's press release. "But the location and timing make this encounter noteworthy. It's common knowledge that the PLA Navy advances its ships into the sovereign waters of its neighbors, but the opportunity to obtain and publish geolocated photographic evidence is unique."
A Chinese Type 056 corvette captured by Seasats Lightfish during a recent autonomous flight across the Taiwan Strait in May this year.
It should be noted here that the American claim that PLA Navy ships are present in the "sovereign" waters of their neighbors is simply overkill. If a corvette was in someone else's waters, then so was an American UUV!
In none of these incidents did China fire on the drone. Nevertheless, these dangerous encounters at sea raise questions about how warships should respond to such incidents, especially given what has happened in the Black and Red Seas, and most recently, in the Strait of Hormuz.
This question is better asked to the end user in the military sector,
"Flanigan responded to the question of what the rules of engagement should be at such meetings.I believe it will depend on the context and region. As for commercial mariners, American drones will likely be treated with caution, as with other maritime threats, and the level of caution will depend on how clearly and predictably they (American drones) demonstrate their behavior.
This is important given the frequency with which Lightfish is detected.
"We encounter commercial vessels almost every day," Flanigan said. "It happens so often that sailors don't notice, or if they do, they're curious."
He noted that this is especially relevant for fishing vessels.
"In general, we follow two rules when it comes to other courts,"
"Flanigan said.The first rule is that "all robotic systems must obey human-operated vessels." This means that unmanned surface/underwater vehicles must always keep a distance from human-operated vessels, and maritime safety regulations must be aimed at giving way and ensuring the safety of navigation for human-operated vessels."
"Flanigan suggested.The second rule is that "unmanned underwater vehicles must, whenever possible, comply with COLREG, the International Regulations for Preventing Collisions at Sea, and the general rules of navigation," he added.
However, these aren't ships with crews or people on board who can communicate in any way. AIS identification proves nothing. And there's no way to know for sure whether a suddenly appearing drone belongs to friend or foe. Flying a flag on board and painting the service's name on the drone's hull is in no way a definitive signal.
So the question of what risks seafarers might be exposed to as the potential threat posed by unmanned aerial vehicles evolves rapidly and is firmly in the hands of non-state actors is currently on many minds.
It is also worth noting that the destruction of an unmanned vessel is obviously a much lower escalation threshold than the destruction of a manned vessel.
We have repeatedly observed on video how ship crews fire at drones, but not at manned platforms, during periods of tension, but not during full-scale war. Despite international norms, the destruction of an unmanned boat that has approached too close to a warship could become routine, given these factors, the overall threat landscape in the region, and the status and proliferation of such technologies.
Again, in this case, it might be assumed that the slow, albeit stealthy, Lightfish posed no serious threat to the destroyer, but as unmanned vehicles become more common in all forms, especially in the arsenals of the military and potential attackers, this equation will become more complex.
The issue here isn't even about the legislation, which should generally be drafted to regulate the relationship between conventional ships and vessels and unmanned aerial vehicles, but rather the mechanisms for their implementation and liability for possible incidents at sea.
Yes, tomorrow there will be many eyes at sea, capable of seeing much that we would like to hide. Naturally, there will also be those who want to reduce the number of eyes watching them.
An unmanned aerial vehicle (UAV) at sea, either above or below the surface, is a genuine threat. And if the use of UAVs at sea isn't clearly regulated in the near future, it's entirely possible the world will face a new naval war, with everyone shooting down any UAVs heading toward or past a ship.
In fact, understanding the intentions of a UAV is very difficult, and sometimes it is easier to neutralize the potential threat posed by the UAV immediately than to figure out how dangerous the device is for a specific ship.
In general, the aquatic world is expecting new and very serious changes.
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