Beneath the ocean’s surface, hidden from view, lies a global nervous system. Thousands of miles of armored cables carry internet traffic, financial transactions, and military communications between continents. Now, in a rare admission, China has revealed a tool that could, with surgical precision, sever these vital links at depths once thought unreachable.
The compact, powerful tool is capable of severing even the most heavily fortified deep-sea communication and power cables. Developed by the China Ship Scientific Research Centre (CSSRC) and its affiliated State Key Laboratory of Deep-sea Manned Vehicles, the device operates at unprecedented depths of up to 4,000 meters — twice as deep as existing cable infrastructure typically extends.
While it’s common knowledge that Russia has similar technology (though not officially reported in this capacity), this is the first time any nation has publicly acknowledged the possession of such a tool.
A Feat of Engineering
Operating at such depths presents formidable challenges. Under pressures exceeding 400 atmospheres — comparable to placing an elephant on your fingertip — the device must remain intact and functional. Engineer Hu Haolong, who led the research published in the journal Mechanical Engineer, described the extraordinary technical demands. Conventional blades fail against the steel-reinforced, polymer-layered cables that underpin 95 percent of global data transmission.
To overcome this, Hu’s team crafted a specialized diamond-coated grinding wheel. Spinning at 1,600 revolutions per minute, this 150-millimeter cutting disk effortlessly grinds through steel sheaths, rubber insulation, and protective polymers without disturbing the seabed.
The cutting tool can fit neatly onto robotic arms aboard China’s advanced submersibles like the Fendouzhe, or Striver, and the Haidou series, vehicles which have been touted as deep-sea exploration and research vessels, but which have long been suspected to carry a dual-purpose. Equipped with a compact, one-kilowatt motor and advanced positioning technology, the tool can function precisely even in near-total darkness, though prolonged use risks overheating.
“Nations are now compelled to redirect their resource exploitation focus towards the seas,” the Chinese 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.”
A Tool for Exploration — or a Weapon of Hybrid Warfare?
Chinese scientists insist their invention is intended primarily for peaceful purposes, such as seabed mining, scientific exploration, and marine resource development. But the line between civilian technology and military capability is alarmingly thin.
Nearly 380 undersea cables stretching over 800,000 miles across the ocean floor quietly and efficiently carry 99% of international communications. Without these cables, global communication, commerce, and government systems would come to a screeching halt.
There is growing suspicion that China may already be testing the strategic impact of cable disruptions. Over the past two years, Chinese vessels have been implicated multiple times in suspicious incidents involving cable damage near Taiwan and even as far away as the Baltic Sea — accusations Beijing repeatedly denies.
In January 2025, Taiwan accused a Chinese freighter of severing a crucial telecom cable off its northern coast. A month later, Taiwanese authorities detained a Togo-flagged vessel. It was suspected of damaging an undersea internet cable connecting Taiwan to its outlying Penghu Islands. The vessel was crewed by eight Chinese nationals. In 2023, Taiwan officials blamed Chinese ships for two incidents in which cables connecting Taiwan’s main island to its outlying islands of Matsu were damaged, causing an internet blackout.
“If I had a nickel for every time a Chinese ship was dragging its anchor on the bottom of the Baltic Sea in the vicinity of important cables,” tweeted Lithuanian Foreign Minister Gabrielius Landsbergis after cables linking Finland, Germany, Sweden, and Lithuania were mysteriously severed, “I would have two nickels, which isn’t much, but it’s weird that it happened twice.”
Indeed, as China demonstrates its technological prowess, some analysts see this cable-cutting device as more than mere coincidence. The South China Morning Post, which first broke this story, warns that China could strategically target cables at critical chokepoints such as Guam, a U.S. military hub and a linchpin to Washington’s Pacific defense strategy. Severing cables there could effectively blind critical communication and logistics channels during a geopolitical crisis.
Undersea Sabotage is a Big Deal
Even minor disruptions to undersea cables can cascade into economic and political turmoil. The Carnegie Endowment, a U.S.-based think tank, warns: “Even a modest disruption in internet connectivity . . . could have drastic consequences for European and global financial markets, which rely on rapid information flows to optimally perform.”
Europe is acutely aware of this threat. Following the suspected sabotage of the Baltic connector gas pipeline in October 2023 — initially denied by Beijing but later admitted as accidental damage by a Hong Kong-flagged Chinese ship — European states have grown wary of the dual-use potential of maritime technologies. A second incident in the Baltic Sea occurred in November 2024. This time, two subsea communications cables connecting Germany and Finland and Lithuania and Sweden, respectively, were allegedly severed by the Yi Peng 3, a Chinese cargo ship.
China’s latest device adds urgency to such concerns. Though designed ostensibly for peaceful marine exploration and resource extraction, its potential military applications loom large. China’s expanding fleet of deep-sea submersibles, now the world’s largest, could deploy the cutter covertly. It would allow then to exploit undersea vulnerabilities without surfacing or leaving immediate evidence.
This ambiguity — civilian tool or/and strategic weapon — makes deterrence challenging. Unlike direct military aggression, sabotaging undersea infrastructure provides plausible deniability. It is, in essence, an invisible act of war.
Whether its intentions are truly peaceful or not, one thing is clear: the silent cables that underpin our interconnected world are now more vulnerable than ever before.
