New undersea cable cutter risks Internet’s backbone - Ars Technica

Overview

New undersea cable cutter risks Internet’s backbone

China cable-cutter demo coincides with more sabotage of subsea Internet cables.

Details

A Chinese ship has tested a new device capable of slicing through submarine data cables thousands of meters beneath the ocean surface. That demonstration may exacerbate security concerns over a spate of suspected sabotage incidents targeting undersea communications and power cables from the Baltic Sea to the Pacific Ocean.

The trial took place at a depth of 11,483 feet (3,500 meters) during a deep-sea science expedition involving the Chinese research ship named Haiyang Dizhi 2, according to the South China Morning Post. That ship is equipped with a 150-ton crane, a 10-kilometer fiber optic winch, and a helicopter landing platform. It has shown the capability to deploy deep-sea remotely operated vehicles in previous missions.

The South China Morning Post cited a report in the China Science Daily, an official, Chinese-language news publication run by the Chinese Academy of Sciences. The latter claimed that “the sea trial has bridged the ‘last mile’ from deep-sea equipment development to engineering application.”

This is the latest of multiple dual-use technologies for cutting undersea cables developed by Chinese military and civilian organizations over the years. Previous examples include People’s Liberation Army naval organizations filing patents for cable-cutting and retrieval tools, as well as Lishui University filing a patent for a cable-cutting device that could be towed behind a vessel for emergency use, according to the Jamestown Foundation think tank based in Washington, DC. Such technology also debuts at a time when a growing number of Chinese-registered ships have been involved in damaging subsea data cables and even pipelines across the world.

The cable-cutting technology is reportedly designed to cut subsea cables at maximum depths of 13,123 feet (4,000 meters). Its design was first published in the Chinese-language journal Mechanical Engineer in 2025 and attributed to researchers at the China Ship Scientific Research Center and the State Key Laboratory of Deep-sea Manned Vehicles.

The submarine cable-cutting technology relies on an electro-hydrostatic actuator consisting of a hydraulic pump, an electric motor, and a control unit. That compact device enables a diamond-coated grinding wheel to exert enough force to cut through undersea cables armored with layers of steel, rubber, and polymer, according to the South China Morning Post’s earlier reporting from 2025. It’s also small enough to fit aboard one of China’s many underwater remotely operated vehicles.

The Chinese “display of deep-sea cable-cutting technology” represented a “show of strength,” said Wendy Chang, an analyst at the Mercator Institute for China Studies in Germany, when the technology initially came to light in 2025.

“From continuing to deny its involvement in shadowy operations involving doctored anchors to unveiling equipment to cut fortified cables, China is sending mixed messages about its role in global submarine infrastructure,” said Chang. “It wants to be a player in its construction and operation—but also wants the world to know that it has the capability to disrupt critical infrastructure if necessary.”

China is not alone in having the technological capability to access and potentially cut undersea cables. During the Cold War, the US Navy used a specially modified submarine and divers to secretly tap Soviet naval communications running through an undersea cable in the Sea of Okhotsk. Both the US and Russia continue to operate nuclear submarines and survey ships equipped with robotic submersibles that could access undersea cables. Some of the latest incidents of accidental or suspected sabotage damage to undersea cables have even simply involved ships dragging their anchors across the seafloor.

The Chinese researchers have insisted that the cable-cutting technology is intended for civilian purposes involving “marine resource development.” But the South China Morning Post has speculated that the tool could pose a threat to the fiber-optic cables linking to Pacific islands such as Guam, the US overseas territory that hosts several military bases.

Such a tool would also exacerbate Chinese military pressure on the self-governing democracy of Taiwan, which relies on 24 major cables for its global connectivity. Taiwan has faced a series of suspected undersea cable sabotage incidents involving Chinese-owned ships as part of a broader pressure campaign by Chinese military and maritime militia vessels, which have conducted multiple exercises in the waters near Taiwan.

Chinese-flagged cargo ships have even damaged undersea data cables and gas pipelines in the Baltic Sea at least twice in October 2023 and November 2024, affecting European countries such as Germany, Finland, Lithuania, Estonia, and Sweden. Chinese officials described those incidents as accidents.

Given the broader pattern of suspected sabotage incidents, it’s not hard to imagine some cause for concern in the newest cable-cutting tool’s dual-use capabilities. It’s also a reminder of the growing vulnerability of the Internet’s physical backbone, which consists of more than 1.5 million kilometers of submarine cables that stretch across oceans and connect continents.

1.          Florida surgeon charged with killing man after removing liver instead of spleen
   

2.          Vulcan woes will "absolutely" be a factor in Pentagon's next rocket competition
   

3.          Google releases new apps for Windows and Mac OS
   

4.          FCC exempts Netgear from ban on foreign routers, doesn't explain why
   

5.          What’s the deal with Alzheimer’s disease and amyloid?
   

Ars Technica has been separating the signal from the noise for over 25 years. With our unique combination of technical savvy and wide-ranging interest in the technological arts and sciences, Ars is the trusted source in a sea of information. After all, you don’t need to know everything, only what’s important.

Key Takeaways

• New undersea cable cutter risks Internet’s backbone

• China cable-cutter demo coincides with more sabotage of subsea Internet cables

• A Chinese ship has tested a new device capable of slicing through submarine data cables thousands of meters beneath the ocean surface

• The trial took place at a depth of 11,483 feet (3,500 meters) during a deep-sea science expedition involving the Chinese research ship named Haiyang Dizhi 2, according to the South China Morning Post

• The South China Morning Post cited a report in the China Science Daily, an official, Chinese-language news publication run by the Chinese Academy of Sciences