China Unveils Powerful 4,000-Metre Deep-Sea Cable Cutter, Raising Fears of Undersea Infrastructure Disruption—All About It

China has introduced a deep-sea cable-cutting device which is capable of cutting the heavily fortified underwater communication or power lines, a development that could significantly impact global maritime security, South China Morning Post reported.

This marks the first known instance of a nation officially revealing possession of a tool capable of disrupting critical undersea networks.

Designed for integration with China’s advanced manned and unmanned submersibles such as the Fendouzhe and Haidou series, he tool, which is able to cut lines at depths of up to 4,000 metres (13,123 feet)—twice the depth of current subsea communication infrastructure.

The device has been developed by China Ship Scientific Research Centre (CSSRC) and its affiliated State Key Laboratory of Deep-sea Manned Vehicles.

The tool is designed to cut armored cables—reinforced with steel, rubber, and polymer layers—that support 95 per cent of global data transmissions.

Although designed for civilian applications such as seabed mining and salvage operations, the device’s dual-use capabilities could raise concerns among other nations.

If deployed near key strategic chokepoints like Guam, a critical node in the US military’s second island chain strategy, the tool could disrupt global communications in times of geopolitical tension.

According to the team led by engineer Hu Haolong, the cutting tool’s design has overcome several formidable technical challenges arising from the deep-sea conditions.

The peer-reviewed paper by the team has been published in Chinese-language journal Mechanical Engineer on 24 February.

Withstanding pressures exceeding 400 atmospheres at 4,000 metres, the device employs a titanium alloy shell and oil-compensated seals to prevent implosion, even under sustained use.

Mounted on submersibles with constrained power budgets, the tool’s one kilowatt motor and 8:1 gear reducer balance torque (six Newton-metres) with efficiency, though prolonged cuts risk overheating.

Operated by robotic arms in near-zero visibility, the tool is also designed to work with advanced positioning technology to avoid misalignment.

China’s unveiling of this device coincides with its growing presence in global undersea infrastructure.

With the world’s largest fleet of manned and unmanned submersibles, China now possesses the ability to access virtually any oceanic region.

Last month, China commenced construction of a deep-sea “space station” in the South China Sea at a depth of 2,000 metres, designed to support at least six people staying for a month.

In contrast, the US is facing challenges in modernising its deep-sea fleet, while Japan’s only crewed submersible, Shinkai 6500, is nearing retirement with no clear replacement.

A vital hub in the United States' Indo-Pacific strategy, Guam houses over a dozen fiber-optic cables serving both military and civilian entities, including Google.

The device’s ability to operate from stealthy unmanned platforms has sparked debate within military circles, particularly after the mysterious sabotage of Russia’s undersea gas pipeline during the Ukraine conflict.

However, Hu’s team maintains that the tool, tested successfully on 60mm-thick cables in ground experiments, is for “marine resource development".

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