China’s New Giant Underwater Drones Could Reach the U.S. West Coast

For generations, U.S. defense planners have viewed the Pacific Ocean as a natural buffer—5,000 nautical miles of water that keeps any conflict with China far from American shores. But Beijing’s development of extra-extra-large uncrewed underwater vehicles (XXLUUVs) is beginning to upend that assumption, raising concerns that the U.S. West Coast could one day face direct pressure in a conflict.

New satellite imagery, defense show models, and intelligence assessments indicate that China is secretly testing two submarine-sized underwater drones that rival crewed diesel-electric submarines in scale. These drones, operating without a human on board, could potentially travel across the Pacific, deploy weapons, or disrupt major maritime chokepoints—offering China a low-risk means of projecting power far from home waters.

A New Tool That Could Change the Pacific Balance

U.S. military strategy in East Asia long relied on the idea that China could not easily send ships or submarines to American shores. Any future conflict—particularly one involving Taiwan—was expected to be fought “forward,” far from U.S. ports and infrastructure.

But China’s new XXLUUVs appear to challenge that logic. According to naval analysts, the two large underwater drones currently under evaluation are:

• Diesel-electric, with massive battery compartments replacing traditional crew spaces

• Equipped with torpedoes, naval mines, and deployable smaller drones

• Roughly the size of a small submarine, making them the largest underwater drones in the world

The drones’ design is comparable in concept to Boeing’s Orca XLUUV, but at a dramatically larger scale.

10,000 Nautical Miles of Range—Enough to Reach California

Technical data presented at a recent Chinese defense exhibition, along with size-based calculations, suggest the drones can travel approximately 10,000 nautical miles—a distance that puts the U.S. West Coast, Alaska, Hawaii, and even the Panama Canal within reach.

The conceptual model displayed by a Chinese shipbuilder highlighted:

• 7,000 nautical miles cruising on diesel engines, likely while snorkeling

• 3,000 nautical miles fully submerged, enabled by a massive bank of modern lithium-iron batteries

• Potential for even greater range if upgraded to lithium-ion batteries

Such endurance far exceeds the submerged range of most advanced diesel-electric submarines. Analysts say the drones could use their long underwater range during the final phase of a journey, helping them slip past anti-submarine defenses between the island chains that surround East Asia.

Not Just a Science Project

Despite the program’s secrecy, several indicators point to China preparing for operational deployment, rather than research alone.

Chinese shipyards typically promote new experimental projects to attract government attention and funding. But in this case, the XXLUUVs are being hidden inside floating docks and tested at a little-documented facility in the South China Sea.

The scale of China’s uncrewed undersea development is also striking. At least eight large underwater drones (XLUUVs) appeared in a recent military parade in Beijing—more than any other navy currently possesses. The presence of two competing XXLUUV designs, tested from the same port, further suggests a procurement competition similar to earlier Chinese drone programs that later entered service.

Potential Missions: From Minelaying to West Coast Disruption

Because they lack crews, the drones cannot replace submarines for complex tasks requiring human judgment. But they excel in high-risk missions, including:

• Minelaying at long distance, possibly with new Chinese deep-water mines

• Interdicting commercial shipping in designated zones

• Surveillance and scouting far from Chinese waters

• Expendable strikes on targets too risky for crewed submarines

The strategic implications are more concerning. Analysts warn that a fleet of long-range XXLUUVs could allow China to:

• Threaten key U.S. ports such as Los Angeles, Seattle, or San Diego

• Disrupt Pacific supply chains during a crisis

• Pressure the Panama Canal, a cornerstone of global commerce

• Force the U.S. Navy to defend its own coastline, reducing its ability to operate in Asia

China’s growing undersea fleet also includes the Type 041 Zhou-class, a hybrid “nuclear-AIP” submarine reportedly using a small reactor for slow, near-indefinite underwater cruising. Some experts believe the Zhou-class and the XXLUUVs may eventually work together to expand China’s reach deeper into the Pacific.

A New Phase in Undersea Competition

The Pentagon has already begun to take notice. While the U.S. is developing its own Orca XLUUV, American programs remain behind China in scale and speed. Defense officials worry that the Pacific—once seen as a protective moat—could become a vulnerability if China fields dozens of long-range drones.

If deployed in significant numbers, China’s XXLUUVs could redefine not just warfare but global shipping security, forcing the United States and its allies to rethink anti-submarine strategies built for a different era.

What once seemed impossible—the prospect of uncrewed Chinese submarines reaching American waters—may soon become a question of when, not if.