What Is China’s Deep-Sea Cable-Cutting Device Raising Global Security Concerns?

China has unveiled a compact, deep-sea cable-cutting device capable of severing some of the world’s most fortified underwater communication and power lines. This revelation marks a significant moment in global maritime capabilities, as no other country has officially disclosed possessing such technology before.

The tool, designed to operate at depths of up to 4,000 meters (13,123 feet)—twice the maximum operational range of most subsea communication infrastructure—has been specifically engineered for integration with China’s advanced crewed and uncrewed submersibles, including the Fendouzhe (Striver) and the Haidou series.

Designed for Civilian Use, But With Strategic Implications

Developed by the China Ship Scientific Research Centre (CSSRC) and its affiliated State Key Laboratory of Deep-sea Manned Vehicles, the device is designed to cut through armored cables that form the backbone of 95% of global data transmission. These cables are heavily reinforced with layers of steel, rubber, and polymer sheaths.

While China maintains that the Deep-Sea Cable-Cutting tool is intended for civilian purposes such as salvage operations and seabed mining, its dual-use potential could raise concerns among global security analysts. If deployed strategically, such a device could disrupt communication networks in key locations, including near Guam, a critical hub for the U.S. military’s second island chain strategy aimed at containing China.

How Deep-Sea Cable-Cutting Device Works

A research team led by engineer Hu Haolong outlined the technical breakthroughs behind the tool in a peer-reviewed paper published in the Chinese-language journal Mechanical Engineer on February 24.

At a depth of 4,000 meters, water pressure exceeds 400 atmospheres, posing significant engineering challenges. To withstand such conditions, the device is encased in a titanium alloy shell with oil-compensated seals that prevent implosion even during extended operations.

Traditional cutting blades struggle against steel-reinforced cables, but Hu’s team devised a solution: a 150mm (six-inch) diamond-coated grinding wheel spinning at 1,600 RPM. This mechanism exerts enough force to grind through steel while minimizing marine sediment disturbance.

The tool is powered by a one-kilowatt motor with an 8:1 gear reducer, balancing torque at six Newton-metres while ensuring energy efficiency. However, prolonged use could lead to overheating, posing operational challenges.

Deep-Sea Cable-Cutting Device: Precision Operation in Extreme Environments

Designed for deployment via robotic arms in near-zero visibility conditions, the tool integrates advanced positioning technology to ensure precise alignment with its target cables. This capability is crucial for operations in deep-sea environments where human oversight is limited.

The unveiling of this cutting tool comes at a time when China is expanding its footprint in undersea infrastructure. Beijing now operates the world’s largest fleet of crewed and uncrewed submersibles, capable of reaching virtually any part of the world’s oceans.

Last month, China also began construction of a 2,000-meter-deep “space station” on the South China Sea’s seabed, designed to accommodate at least six people for extended missions of up to a month.

Meanwhile, the U.S. is facing challenges in maintaining its deep-sea capabilities, with an aging fleet struggling to keep pace with advancements from China. Japan’s sole crewed deep-sea submersible, Shinkai 6500, is also nearing retirement with no immediate successor in development.

Security Concerns Over Potential Strategic Use

Guam plays a crucial role in U.S. Indo-Pacific strategy, housing more than a dozen fiber-optic cables that serve both military and civilian clients, including Google. The potential for China’s tool to operate from stealthy unmanned platforms without surfacing has raised concerns in military research circles. Such a scenario has become increasingly relevant following the mysterious explosion of Russia’s seabed natural gas pipeline during its war with Ukraine.

Despite these concerns, Hu’s team insists that the tool’s primary goal is to aid marine resource development. In their paper, the researchers emphasized the strategic importance of the oceans in shaping future global economic and geopolitical landscapes.

“Nations are now compelled to redirect their resource exploitation focus towards the seas,” the researchers wrote.

“The 21st century is the century of the oceans. Enhancing marine resource development capabilities, advancing the blue economy, and building China into a maritime powerhouse constitute critical components of realizing the Chinese dream.”

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