China unveils underwater ‘kill switch’ for the internet: How this tech could sever global connectivity

deep-sea engineering, unveiling a device capable of slicing through the world’s most reinforced undersea cables at unprecedented depths. Developed by the China Ship Scientific Research Centre (CSSRC) and the State Key Laboratory of Deep-Sea Manned Vehicles, the tool integrates seamlessly with China’s advanced submersibles, including the Fendouzhe (Striver) and the Haidou series.

For the first time, a country has openly declared possession of such a device—one that can target undersea infrastructure vital to global communication and military operations. These cables transmit 95% of the world’s data, linking continents and ensuring the smooth functioning of financial markets, defence systems, and everyday digital services.

How the Device Works

Traditional underwater cable-cutting techniques struggle against steel-reinforced lines. To overcome this, the Chinese team, led by engineer Hu Haolong, designed a 150mm (six-inch) diamond-coated grinding wheel rotating at 1,600rpm. This mechanism generates enough force to shatter steel while minimising seabed disturbances. The tool is powered by a one-kilowatt motor with an 8:1 gear reducer, ensuring efficient torque distribution, though prolonged use at such depths could lead to overheating.

To function in extreme conditions, the cutter is enclosed in a titanium alloy shell with oil-compensated seals, preventing implosion under the crushing pressure found at 4,000 metres. Operated by robotic arms in near-zero visibility, the device relies on advanced positioning systems for precision.

Potential Military Implications

While officially promoted as a tool for seabed mining and salvage operations, the device’s dual-use nature has sparked concerns in security circles. The ability to