There is a quiet revolution happening under the world’s oceans. Most people are unaware of it, but military strategists in Washington, Tokyo, and Taipei are paying close attention. This revolution revolves around a new type of weapon that China has been secretly developing, testing, and now publicly showcasing: extra-large, autonomous, unmanned underwater drones. There is no crew, no noise, and no warning.
These machines do not resemble the sleek, futuristic robots seen in science fiction. They appear more like huge torpedoes, long, cylindrical, and completely silent. However, their simplicity is misleading. China’s extra-large underwater drones mark one of the most significant changes in naval warfare in decades. It’s important for every informed reader to understand what they are, what they can do, and why they matter.
The Rise of China’s Underwater Drone Program
To understand how dramatic China’s progress has been, you need to look back a few years. When China introduced its first large underwater drone for the Navy in 2019, the 5-meter-long HSU001, it seemed to be making only small advancements in autonomous undersea warfare. At that time, Beijing was clearly behind the top Western navies.
That was 2019. Six years later, the picture has completely reversed.
China’s development of extra-large uncrewed underwater vehicles (XLUUVs) is now unmatched worldwide and moving forward quickly. No other country is working on undersea autonomy on a similar scale, scope, or speed.
The HSU001 was similar to the U.S. Navy’s large displacement UUV. It was intended for missions like gathering intelligence and anti-submarine warfare. At about 7 meters long, it was less than half the size of “Orca,” the U.S. Navy’s Extra Large UUV. Orca is made for complex, long-distance missions, including delivering specialized payloads such as mines, seabed sensors, and small UUVs.
Understanding China’s Underwater Drones
Before going further, it helps to understand the terminology, because the naming conventions matter.
UUV stands for Uncrewed Underwater Vehicle — any autonomous or remotely operated submarine-like device without a human crew aboard.
XLUUV stands for Extra-Large Uncrewed Underwater Vehicle — a much bigger category, typically capable of carrying weapons, traveling long distances, and operating for extended periods without human intervention.
XXLUUV (or “Extra-Extra-Large”) is a newer term analysts have coined because even “extra-large” turned out to be an inadequate description for what China is now building.
The term currently used for larger underwater drones, XLUUV, doesn’t do these new vessels justice. It was never wise to use “XL” in a name since it was clear that people would eventually create much larger ones. The latest Chinese models are about 10 to 20 times bigger than what is considered an XLUUV in Europe.
To put it plainly, these are not small gadgets. China is believed to have built large submersible XLUUVs, which satellite images show are about 130 feet, or roughly 40 meters, long. Newsweek reports that this is the size of some countries’ standard crewed submarines.
The 2025 Parade That Shocked the World
For years, China’s underwater drone program operated in the shadows. The outside world got occasional glimpses through satellite imagery, open-source intelligence, and defense analysts poring over shipping records. Then, on September 3, 2025, China decided it was time to show the world what it had built.
At a massive military parade in Beijing’s Tiananmen Square marking the 80th anniversary of the end of World War II, Chinese President Xi Jinping, Russian President Vladimir Putin, and North Korean leader Kim Jong Un looked on as the People’s Liberation Army sent a parade of soldiers and military equipment past the square.
Bracketing what a commentator for the state-owned China Global Television Network called the PLA’s “unmanned maritime combat formation” were two new models of extra-large uncrewed underwater vehicles, cigar-shaped submarines roughly the length of an 18-wheeler.
Two specific models were revealed to the public for the first time: the HSU100 and the AJX002.
The HSU100
Leading the unmanned naval column was the HSU100 extra-large unmanned underwater vehicle, fitted with retractable sensors likely intended for intelligence, surveillance, and reconnaissance operations. The HSU100 is estimated to measure perhaps 15 meters long. Asian Military Review It is a thicker, more heavily built platform, believed to be designed for heavier payloads and longer endurance.
Key specifications and features include:
- Length: ~15 meters
- Diameter: ~2–3 meters
- Propulsion: Ducted propeller with X-form rudders at the stern
- Sensors: Two retractable masts that rise from a hatch on top of the hull, equipped with electro-optical and electromagnetic sensors for surveillance
- Sonar: Prominent flank array sonar along the hull and a large bow aperture likely housing a passive sonar array
- Payload capacity: Wider hull designed to carry heavier payloads and support longer endurance missions compared to the AJX002
- Primary mission: Long-range intelligence gathering, undersea surveillance, and anti-submarine warfare (ASW)
What makes the HSU100 particularly significant is its sensor suite. The combination of retractable masts, flank sonar, and bow sonar means it can simultaneously monitor surface activity, track enemy submarines, and relay intelligence — all without a single crew member aboard.
The AJX002
Following the HSU100 was the AJX002, a smaller-diameter but equally long XLUUV that features a notably clean profile without any visible retractable sensors. Analysts speculate the torpedo-like XLUUV uses pump-jet propulsion to lower its acoustic signature and extend its range. It also has cruciform rudders for low-speed maneuvering, such as seabed operations or for stealthy missions that involve loitering.
Key specifications and features include:
- Length: 18–20 meters (~60–66 feet)
- Diameter: 1–1.5 meters
- Propulsion: Pump-jet system — the same technology used in the world’s quietest nuclear submarines — producing significantly less acoustic noise than conventional propeller systems
- Maneuverability: Cruciform rudders at the stern for precise low-speed control during seabed operations and covert loitering missions
- Power source: Approximately half the hull is dedicated to lithium-based batteries, enabling extended autonomous operation
- Range: Estimated at approximately 1,000 nautical miles (1,800 km), possibly significantly more according to Naval News
- Deployment: Four lifting lugs on the hull indicate crane-assisted pier-side launch capability, allowing it to be deployed from multiple locations including ports and surface vessels
- Primary mission: Dedicated mine-laying system — officially confirmed by Chinese state commentary during the parade
The official Chinese commentary described the AJX002 as a mine-laying system. This dedicated platform changes how China can lay mines. It also increases the chances that they will use them.
Based on its size and the performance of similar systems, the AJX002 likely has a range of about 1,000 nautical miles, or roughly 1,800 kilometers. It might even have a longer range. This estimate comes from the fact that about half of its hull is filled with lithium-based batteries.
China’s Even Larger Underwater Drones
If the parade models alarmed Western analysts, what came next alarmed them even more. While Beijing was showcasing the HSU100 and AJX002, defense researchers were tracking something even larger in the South China Sea.
China has built two similarly sized drone submarines and is testing them together in the South China Sea. The two new uncrewed submarines are being tested in waters around Hainan, temporarily based in Gangmen Harbour, which is west of the main naval base at Sanya. This is the same location where Chinese nuclear submarines, aircraft carriers, and other large uncrewed underwater vehicles have been seen.
Technically called Extra-Extra-Large Uncrewed Underwater Vehicles (XXLUUVs), these drones are similar in size to traditional diesel submarines, but they operate on their own. Since they do not need space for human crews, they can use that space for fuel, batteries, sensors, and weapons. They are also said to have very long ranges, which means they could travel across the Pacific Ocean and stay in one place for extended periods.
China’s XXLUUVs will have an operational range of about 10,000 nautical miles. The designs will likely be diesel-electric, featuring a diesel generator and a large bank of batteries that occupy most of the hull volume instead of crew space. The claimed submerged range of 3,000 nautical miles is much greater than that of conventional submarines. Thanks to these huge banks of modern batteries, they can travel about six times further underwater than the best diesel-electric submarines.
Why China’s Underwater Drones Matter
To understand why military experts are paying such close attention to China’s extra-large underwater drones, you need to understand the strategic logic behind them.
Going Where Submarines Won’t
China’s nuclear-powered submarines can theoretically operate in the Eastern Pacific, close to the U.S. coastline. However, they seldom do so because they are too valuable and needed in other areas. Sending crewed submarines on dangerous, long-distance missions poses significant political and strategic risks if one is found or, worse, lost.
Unmanned drones carry no such risk. These large underwater drones could enable China to blockade the West Coast of the United States, or even the Panama Canal. China’s nuclear-powered submarines already have this range on paper, but they are not reported to operate in the Eastern Pacific. This is likely because they are too valuable and needed for other roles.
Targeting America’s Underwater Sensors
One of the most important, yet least talked about, strategic uses of these vehicles is targeting the U.S. undersea sensor network. The U.S. military has spent decades creating a complex web of hydrophone arrays, seabed sensors, and underwater surveillance systems across the Pacific. This network is a key tool for tracking Chinese submarines.
Citing People’s Liberation Army Navy officers in the Military Art journal, analysts say Chinese submarines face a “fairly high probability” of detection during peacetime operations, even within the First Island Chain.
The U.S. Navy’s integrated surveillance system, which includes seabed sensors, satellites, aircraft, and unmanned vehicles, can track PLAN submarines from port to patrol. This constant exposure undermines their stealth, which is the main advantage in submarine warfare, and raises concerns about operational effectiveness.
China’s XLUUVs offer a solution. China is exploring means to disable the U.S. undersea sensor network, including deploying remotely operated vehicles to sever cables, autonomous submarines to plant explosives, and long-range underwater drones capable of delayed activation via acoustic signals.
China’s Underwater Drones and the Taiwan Blockade
No discussion of China’s undersea drone program would be complete without mentioning Taiwan. This small island democracy is at the center of a major geopolitical conflict in the Asia-Pacific. China’s large underwater drones are partly developed with Taiwan as a focus.
A 2024 report by the Center for Strategic and International Studies found that secret mine-laying operations near Taiwanese ports would be vital to China’s efforts to isolate the island. Brian Hart, deputy director of the China Power Project at CSIS, said that China’s new XLUUVs could serve this purpose. He also mentioned that the main feature that distinguishes XLUUVs from smaller models is their capacity to conduct long-range missions.
Taiwan is very vulnerable to an attack on its undersea cables. The island relies on just 24 undersea cables for internet access. Cutting these cables could disrupt everything from banking to emergency services. If China were to sever Taiwan’s undersea cables, it could create a blockade. This would cut off the island’s energy, food, information, and essential services, forcing it to surrender without any violence.
Is the United States Keeping Up?
The U.S. is not standing still. Boeing’s Orca XLUUV is in development, and the Navy plans to expand its unmanned undersea fleet. However, American analysts are becoming more honest about the fact that China’s program is moving faster than the U.S. response.
Michael Montgomery, a former U.S. Navy officer who has been following recent XLUUV developments, suspects that the U.S. is falling behind. “My gut reaction is they’re probably moving faster than the United States,” he said. “I’ve heard us talk about building dozens of XLUUVs over time. If we can do that, they can build hundreds.”
The production capacity gap is real. There were eight XLUUVs present at the recent military parade in Beijing — five AJX002 minelayers and three larger HSU100s. Other navies don’t have eight XLUUVs at all. That line deserves to sit with the reader for a moment. Every other navy in the world combined does not possess as many operational XLUUVs as China paraded through its capital in a single afternoon.
Why These Drones Are Hard to Counter
One of the most troubling aspects of this technology is how hard it is to defend against. Traditional anti-submarine warfare depends on detecting the acoustic signature of a submarine, the hum of its propellers, the sound of its machinery, and the noise of its crew. Unmanned vehicles remove much of that.
Analysts believe that the AJX002 uses pump-jet propulsion to reduce its acoustic signature and increase its range. Asian Military Review Pump-jet propulsion is the same technology found in some of the world’s quietest nuclear submarines. This is mainly because it produces much less detectable sound than traditional propeller systems.
“It’s a very hard target,” said Lyle Goldstein. “I think Taiwan has its hands full, really, in all respects.”
The modular design of these vehicles adds another layer of complexity. Modular construction, lifting lugs for cranes, and truck-based transport suggest these UUVs were built to be moved and launched from multiple ship types or shore facilities. That modularity would let the PLAN increase operational flexibility and complicate adversary tracking prior to deployment.
The Ocean Floor as the New Battlefield
What China is building is not just a weapon. It is a completely new theory of naval warfare. This theory risks no sailors, operates at ranges once reserved for nuclear submarines, and challenges every traditional assumption about ocean defense.
Lyle Goldstein of the U.S. Naval War College summed it up simply: “We’re talking about, if not a revolution in naval warfare, then something approximating one.”
The implications go well beyond Taiwan. These platforms could one day act as nuclear delivery systems. They might avoid U.S. missile defenses, and could be sold to other countries. This would permanently change the global balance of power under the sea.
China already has the world’s largest navy. The ocean floor is the next battlefield. And right now, China is writing the rules.
This article is for informational and educational purposes. All data referenced is drawn from open-source defense analysis, satellite imagery studies, and reporting by credentialed naval affairs specialists.
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