Revealed: China's new weapon that can cut any undersea cable

Telegraph

24-03-2025

Chinese researchers have developed a compact, deep-sea device capable of severing even the most fortified underwater cables.
The development raises concerns that Beijing could target critical communication and power lines, especially in the event of a Chinese invasion of Taiwan.
The tool can slice armoured cables at depths of up to 4,000 metres (13,123 feet), which is twice the maximum operational range of existing subsea communication infrastructure, according to an academic paper seen by the South China Morning Post.
While the cutting tool was developed for civilian salvage and seabed mining, it will raise alarm bells amid fears China and Russia are becoming increasingly brazen in deploying 'grey zone tactics' to assert their influence and isolate adversaries.
The new technology contains a six-inch diamond-coated grinding wheel, which can spin at 1,600rpm – giving Beijing the ability to slice through deep-sea cables layered with steel, rubber and polymer sheaths.
These underpin roughly 95 per cent of global data transmission and have emerged as a key vulnerability for governments in an era of geopolitical instability.
The tool – developed by the China Ship Scientific Research Centre and the State Key Laboratory of Deep-sea Manned Vehicles – has been designed to be integrated into the crewed and uncrewed submersibles China already has.
The technology is also armed with a titanium alloy shell, while oil-compensated seals prevent the tool from imploding because of the intense water pressure found 4,000 metres underwater.
Robotic arms have been designed to operate with advanced positioning technology to ensure accuracy despite limited visibility in the depths.
Beijing 'much more brazen'
The paper summarising the technology was published in a Chinese-language journal called Mechanical Engineer in February, according to the South China Morning Post, and it is the first time that any country has officially confirmed access to an asset of this type.
The authors of the report insisted that the tool is a resource to assist maritime development.
'Nations are now compelled to redirect their resource exploitation focus towards the seas,' they 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 realising the Chinese dream.'
But its existence will raise alarm bells internationally.
Beijing already has the world's largest fleet of crewed and uncrewed submersibles and last month began construction of a 2,000-metre-deep 'space station' at the bottom of the South China Sea.
But there have also been mounting accusations that China, alongside Russia, is targeting the underwater cables that power global energy flows and communications.
Raymond Powell, a retired US Air Force colonel and founder of SeaLight, a maritime transparency project at Stanford University, told The Diplomat last month that 'we are witnessing a much more brazen Beijing'.
'China continues to expand its already vast grey zone toolkit, having long ago calculated that its willingness to blur the lines between peace and hostilities provides it with an asymmetric advantage,' he said.
'Cable and pipeline sabotage is more than mere harassment. It is a reminder that Beijing has the ability to cause far more damage to its enemies, should it choose to do so.'
He also pointed to a new strategy, where Beijing deploys third-country flagged cargo vessels to sabotage undersea cables, allowing it a degree of deniability.
For instance this year, Taiwan has already reported five cases of cable malfunctions – compared to just three each in 2023 and 2024. In February, the island's government seized a Togo-flagged cargo ship crewed by Chinese workers, called Hong Tai 58, amid suspicions that it deliberately severed an undersea telecom cable.
China, which claims Taiwan as part of its territory, has piled military pressure on the self-governing island in recent years, deploying warships and fighter jets to simulate a future blockade and an invasion.
Analysts say China would deploy grey zone tactics, working to isolate Taiwan, before launching any military invasion of the island.
China is not alone in this tactic: there have been 11 incidents of underwater cable damage in the Baltic Sea since 2023.
'What we appear to be seeing is a growing Russia-China grey zone collaboration, perhaps moving in the direction of a full-fledged 'axis',' said Col Powell.
He said this helps the two superpowers maintain a 'layer of deniability'.
But other regions and countries may also be at risk. The new super-deep cable cutter could target strategic points near Guam, for instance, a cornerstone of the US military's Indo-Pacific strategy which hosts more than a dozen civilian and defence fibre-optic cables.