Key Points and Summary – China unveiled new, massive underwater drone submarines (XLUUVs) at its military parade this week, signaling a new front in the undersea competition with the U.S.
-These semi-truck-sized drones are designed to counter a key American advantage: its sophisticated network of undersea sensors.
-Citing internal Chinese military writings, the piece reveals that Beijing sees this U.S. network as a critical threat to its own submarine fleet.
-The new XLUUVs are the weapon to neutralize it by targeting vulnerable sensor arrays and cables—the system’s “Achilles Heel”—to blind the U.S. in a potential conflict.
What Kind of Threat Do Chinese Underwater Drones Pose For The Navy?
This Wednesday morning, Chinese President Xi Jinping, Russian President Vladimir Putin, and North Korean President Kim Jong-un watched as the People’s Liberation Army and Navy (PLAN) sent an enormous parade of soldiers and military equipment past Tiananmen Square in Beijing.
The three leaders, along with the Presidents of Iran and Azerbaijan, showed a united front against the United States. And it was a huge opportunity for China to showcase its military equipment in a giant sales pitch.
But the most menacing image may have been a new group of weapons China has put on parade, rolling out giant drone submarines to put its undersea ambitions in the open that could one day strike at the US undersea sensor network and tilt the balance of the Pacific’s silent war.
Naval News recently reported that China was expected to unveil two new extra-large uncrewed underwater vehicles (XLUUVs) during a September 3 military parade in Beijing marking the 80th anniversary of the end of the Second World War.
China and Russia always seem to downplay US involvement, despite the fact that both were largely equipped by the US, not to mention the fighting the US did to fight Japan. Russia didn’t even declare war on Japan until after the second atomic bomb was dropped.
The unveiling was the first public appearance of these unmanned assets and will seek to signal China’s rapid progress in underwater drone technology.
China’s New XLUUV Drones
China’s new XLUUVs are about 18-20 meters long (the length of a semi truck) and are generally torpedo-like, with pump jet propulsion. This makes them similar in overall size and shape to the Russian Poseidon nuclear-armed, nuclear-powered torpedo.
China’s Navy (PLAN) has the most extensive XLUUV program of any nation, with at least five types in the water for several years.
It is almost certain that the XLUUVs seen being tested in China are not nuclear-powered. The AJX-002 giant submarine drone could be used to do surveillance and reconnaissance missions.
Chinese developers are pursuing a multi-purpose approach, enabling the AJX-002 to perform reconnaissance, transport, or strike missions. The strategic implications of such a system are far-reaching.
USS Connecticut Seawolf-Class Submarine. Image Credit: Creative Commons.
A nuclear-capable Chinese UUV would add an asymmetric layer to its deterrence posture, complicating US and allied naval planning in the Indo-Pacific.
Militarily, it could be used to threaten high-value naval formations and coastal infrastructure, forcing adversaries to consider new layers of anti-submarine defense.
This drone development signals China’s determination to diversify its deterrent beyond ballistic missiles and submarines, reinforcing its ambitions to contest US maritime dominance. The appearance of multiple units at parade rehearsals also suggests a mass-production intent rather than a one-off prototype, underscoring Beijing’s resolve to push forward in autonomous naval warfare.
A second type, the HSU100, is about the same length but significantly wider, roughly 3 meters across. Unlike the AJX002, which has none, the HSU100 is fitted with two masts. It is yet unknown what this drone will be tasked with or what the significance of the masts is.
These large underwater drones are perfectly designed for use in the immense Pacific Ocean, said Mark Montgomery, retired US Navy rear admiral and senior fellow at the Foundation for Defense of Democracies.
“These are pretty damn big. You could put a lot of fuel in them,” he said, adding, “You may or may not see it enter the water in a maritime base, and you don’t really know where it’s at. Ten hours later, it could be almost anywhere.”
In a 2024 report on how a Chinese blockade of Taiwan would unfold, the Center for Strategic and International Studies (CSIS) found that covert mine-laying operations around Taiwanese ports would be crucial to China’s efforts to isolate the island. China’s new XLUUVs could serve that purpose or several others.
The US continues to work on its own XLUUVs.
Targeting The US Undersea Sensor Network
These new drones will be used to target American undersea sensor capability, which the Chinese know is a direct threat to their submarine forces. Defense News recently wrote that during a time of war, the People’s Liberation Army Navy (PLAN) officers are advocating a systematic attempt to destroy America’s undersea sensor network.
This includes destroying, sabotaging, or spoofing underwater microphones using a variety of countermeasures, from undersea drones to China’s massive fleet of commercial fishing vessels.
During the mid-2000s, US undersea surveillance in the western Pacific was centered on the Fish Hook Undersea Defense Line, a modern chain of fixed arrays to monitor Chinese submarines transiting between the East and South China Seas and the Pacific.
This was written by Desmond Ball and Richard Tanter, in their 2015 book “The Tools of Owatatsumi: Japan’s Ocean Surveillance and Coastal Defense Capabilities.”
The Chinese PLAN is building up its submarine fleet for potential deterrence and warfighting. However, this entirely hinges on the PLAN’s submarines being able to operate undetected by US sensors. The Chinese naval officers recognize this.
Writing in the November 2023 issue of Military Art, a journal published by the Chinese Academy of Military Science, three PLAN officers revealed that the peacetime operations of Chinese submarines are highly vulnerable to the US Navy’s undersea surveillance system, raising serious questions about their strategic and operational utility.
Entitled “Effectively Responding to the Threat to China’s Undersea Space Posed by the Powerful Enemy’s Three-Dimensional Surveillance System,” the article deserves special attention for two main reasons. First, while not an official assessment as might appear in a “white paper” or a “five-year plan,” it reflects the opinions of PLAN experts whose views are informed by access to classified intelligence and subject to peer review.
The first author, Senior Captain Zhang Ning, is a faculty member at the Naval University of Engineering, College of Weapons Engineering. He co-authored the piece with Commander Zhang Tongjian, from the 3rd Destroyer Flotilla (Unit 91257), and Lieutenant Fan Zhaopeng of the PLAN Oceanographic and Meteorological Center (Unit 91001).
Second, the publication in which the article appears—Military Art—is an internal PLA journal. This enables the authors to share their expertise with a candor that is rarely, if ever, seen in publicly available PLA sources.
The US Undersea Sensor System
The Chinese authors wrote that the United States, referred to in the article as the “powerful enemy,” has employed an “integrated, three-dimensional surveillance system” within and around the First Island Chain.
The system combines sensors and platforms located ashore, on and below the ocean, and in the air and space.
Under the sea, the system comprises both fixed and mobile surveillance equipment, including unmanned underwater vehicles (UUVs) capable of carrying a range of payloads.
On the surface of the ocean, the system incorporates US Navy ships, especially ocean surveillance vessels. In the air, the system relies on fixed and rotary wing aircraft equipped with anti-submarine warfare (ASW) sensors.
In space, it leverages ocean surveillance satellites, electronic reconnaissance satellites, and imaging reconnaissance satellites in near-earth orbit. The components, or “nodes,” of the system are connected via satellite communications and Raytheon’s real-time submarine communications system, “Deep Siren.”
However, Chinese naval officers believe that “the U.S. undersea surveillance system suffers from a number of vulnerabilities, amplified by the sheer scale of the Western Pacific battlespace,” Ryan Martinson, a professor at the China Maritime Studies Institute at the U.S. Naval War College, wrote in an essay for the Center for International Maritime Security. “If enough nodes are degraded, the system as a whole may lose its functionality.”
US war planners fear that the Chinese Navy will reach 80 submarines by 2035. Chinese officers worry that an intensive American anti-submarine warfare, or ASW, effort has already made Chinese subs too vulnerable.
The Chinese Navy officers fear that Chinese submarines are vulnerable to what they depict as an “integrated, three-dimensional surveillance system.”
This includes warships, subs, aircraft, satellites, underwater drones, the undersea microphones of the Integrated Undersea Surveillance System, or IUSS, and surface ships hauling the Surveillance Towed Array Sensor System, or SURTASS.
Where America sees a Chinese underwater wave of submarines, China sees an American bid to achieve “unilateral transparency” under the waves. As China sees it, this ASW dragnet is so broad that it uses survey ships to map undersea terrain and water conditions for optimal submarine detection, and oceanic surveillance vessels to capture submarine acoustic signatures.
This is where the XLUUVs enter the picture. China recognizes that the individual components of the US ASW puzzle can be easily compromised through kinetic action, drone use, or cyber warfare, and may also exploit another potential aspect of the XLUUVs.
Chinese officers describe this as the US Achilles Heel of their ASW network, because the cables and arrays are easily severed under the ocean.
The Chinese Navy recognizes the threat that the US ASW poses against its submarines. And the XLUUVs are just a part of their solution.
About the Author: Steve Balestrieri
Steve Balestrieri is a National Security Columnist. He served as a US Army Special Forces NCO and Warrant Officer. In addition to writing on defense, he covers the NFL for PatsFans.com and is a member of the Pro Football Writers of America (PFWA). His work was regularly featured in many military publications.
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