- China has tested an electro-hydrostatic actuator with a diamond saw capable of cutting cables and pipes at a depth of 3.500 meters.
- The technology is presented as a civilian maintenance tool, but its dual-use potential generates strong geopolitical concerns.
- Submarine cables carry almost all international data traffic, so this capacity directly impacts the global digital economy.
- Governments and operators will need to strengthen surveillance, redundancy, and legal frameworks to protect an increasingly vulnerable critical infrastructure.
An increasingly decisive part of the game is being played out at the bottom of the sea. contemporary geopolitics and digital securityBeneath thousands of meters of water runs a vast network of fiber optic cables and pipes that support the daily operation of the internet, military communications, financial markets, and the global economy. Until recently, the main defense of this infrastructure was precisely its depth: physically reaching it was so complicated and expensive that it was considered relatively safe from direct sabotage.
That supposed safety net has faltered after the test of a electrohydrostatic actuator (EHA) developed in ChinaIt is capable of severing underwater structures, including armored data cables, at depths of 3.500 meters and even deeper. The test, conducted from the research vessel Haiyang Dizhi 2, has triggered alarm among governments, telecommunications operators, investors, and defense analysts, because it makes very real a threat that until now was seen more as theoretical than operational.
What exactly has China tested at the bottom of the ocean?
The central piece of this whole affair is a deep water electrohydrostatic actuator Designed by engineers at Zhejiang University, this type of device integrates the hydraulic pump, electric motor, and control electronics into a single unit, all sealed within a compact, reinforced housing to withstand extreme pressures and saltwater corrosion. Eliminating external oil lines and long umbilicals to the surface improves reliability, maneuverability, and discretion.
During a scientific mission on April 11, 2026, the Haiyang Dizhi 2 deployed this system on the seabed and carried out a test that, according to the official newspaper China Science Daily"It filled the last mile between equipment development and engineering application." In other words, the prototype is no longer just a laboratory experiment; it's ready for real-world use in underwater engineering operations. Chinese authorities have presented it as a successful technology demonstration, highlighting that the device can operate stably at pressures exceeding 35 megapascals, equivalent to a depth of about 3.500 meters.
The technology combines this EHA block with a very particular cutting tool: a diamond-coated abrasive wheel or discSimilar to an ultra-reinforced circular saw, it is capable of rotating at around 1.600 revolutions per minute. Thanks to the force applied by the actuator—more than 50 kilonewtons, according to some technical analyses—the tool can penetrate the shielding of submarine cables and large-diameter pipes in a very short time.
The published tests indicate that the system is small enough to be mounted on unmanned underwater vehicles Moderately sized remotely operated vehicles (ROVs) or underwater drones can be deployed without the need for large support vessels or bulky hydraulic equipment on the surface. This opens the door to more discreet, cheaper, and faster operations, both in civilian and, potentially, military environments.
Chinese technical and media literature also mentions that the technology is designed to activate gripping claws and other handling tools In deep water, not just cutting discs. That would make it possible not only to section, but also to move, hold, and work on oil pipelines, metal structures, underwater mining modules, and even cable segments.
How a deep-water electrohydrostatic actuator (EHA) works
The heart of the system is a sealed electrohydrostatic actuatorUnlike conventional hydraulic systems, where pressure is generated at the surface and transmitted through long, oil-filled hoses, the EHA has the pump and fluid enclosed within its own housing. An internal electric motor powers the pump, which pressurizes the fluid and drives a piston or mechanism that, in turn, applies force to the working tool (in this case, the diamond saw).
This compact architecture drastically reduces points of failure: There are no external pipes that could burst. Because of the pressure, there are no multiple leaking connections, nor is there a constant dependence on a large surface vessel pumping fluid. The EHA is controlled by electrical and data signals traveling through a relatively thin cable, or even by acoustic communication, making the system much easier to mount on an underwater drone.
At altitudes between 3.500 and 4.000 meters, the pressure exceeds 35 MPa (about 350 atmospheres), so the entire assembly is manufactured with corrosion and crush resistant materialsand is carefully sealed to prevent water ingress. The control electronics are protected in pressurized or oil-filled compartments, common techniques in deep-sea engineering to prevent pressure from destroying components.
The diamond cutting disc is designed to act on very hard and complex structuresThis tool can cut through materials such as the layers of steel, rubber, polymers, and fiber optic core of submarine data cables, or the walls of steel pipes up to 38 inches in diameter. It spins at around 1.600 rpm, fast enough to slowly eat through the material without causing uncontrollable vibrations, but slow enough to manage heat and wear. The developers themselves acknowledge the risk of overheating if the cutting process is prolonged, so the design strikes a balance between speed and stability.
According to previous tests conducted at a lower level, initial versions of this type of tool They managed to cut the damaged pipes in about 20 minutes.This is in contrast to the more than five hours required by traditional imported equipment. This improvement in time, coupled with the leap in operational depth, illustrates the rapid pace at which the technology is being refined.
Why 3.500 meters (and up to 4.000) change the rules of the game
The 3.500-meter elevation, with a potential capacity up to 4.000 meters, is not a mere specification detail; it is the range in which it is located. a large part of the oceanic route of international cablesWhen the cables move away from the coast and cross the open ocean, they descend to the abyssal plain, which is usually between 3.000 and 5.000 meters deep. It is precisely there where physical access has traditionally been most difficult.
Until now, any intentional damage to submarine cables was primarily associated with coastal areas or shallower waterswhere trawling, anchors from large vessels, or even illicit activities could affect the infrastructure. But the heart of the global communications system remained relatively protected due to the technical difficulty of intervening at those extreme depths, where each operation requires highly specialized ships, favorable weather windows, and weeks of planning.
With tools like the EHA tested by China, that supposed natural shield erodes. A proven capacity to cutting armored cables between 1.500 and 4.000 meters This means that almost the entire global network of underwater fiber optic cables —more than 95-99% of international data traffic passes through it, according to sources— is, in theory, within reach of a drone equipped with this system.
This doesn't mean that any actor can simply go and cut cables; it requires ships, know-how, logistics, and, above all, the political will to assume the risk. But it does imply that a major power with solid naval and technological capabilities could, in a context of tension, to physically intervene in the planet's key infrastructure from depths where detection and attribution are very complicated.
The very chronology of Chinese developments is revealing: in 2022, pipeline repair teams took five hours to cut an 18-inch pipe; in 2023, remotely operated vehicles cut 38-inch pipes at 600 meters and completed repairs in 20 minutes; in 2026, the device is already operating at 3.500 meters. In just four years, operational depth has increased almost sixfold. and intervention times have been reduced by more than 90%.
Submarine cables: the physical backbone of the Internet and the economy
It's worth remembering exactly what's at stake. Submarine fiber optic cables are the backbone of international connectivityThey handle approximately 95-99% of global data traffic: internet, voice, messaging, banking transactions, algorithmic trading, private corporate networks, intercontinental military communications, and much more. The "cloud" layer rests, quite literally, on glass buried at the bottom of the sea.
It is estimated that there are approximately 600 submarine cable systemsWith a total length exceeding 1,5 million kilometers, the equivalent of about 30 trips around the Earth, organizations like the International Cable Protection Committee (ICPC) have been warning for years that between 100 and 200 incidents of cable damage or disruption occur annually, the vast majority due to accidental causes: anchor dragging, fishing activity, geological movements, storms, etc.
In recent years, however, attention has shifted towards the risk of sabotage or deliberate interferenceEpisodes like the Mysterious damage to telecommunications cablesThe cutting of cables in the Red Sea in 2025 and the movements of Russian submarines around key cable lines have focused attention on the seabed as a potential site for covert operations. The testing of the Chinese actuator, therefore, comes at a time when sensitivity surrounding this issue was already very high.
For countries like Taiwan, with its global connectivity supported by just 24 large submarine cables, the situation is especially delicate. The island has suffered several cable cuts attributed to Chinese ships.Officially attributed to accidental incidents, these events are interpreted as strategic pressure tactics. Meanwhile, in the Baltic Sea, "mysterious" damage has been reported to gas pipelines and data cables in areas where Russian and Chinese-flagged vessels were also operating.
Civilian applications: repair, energy and deep-sea mining
China insists that the EHA and its diamond saw have a primary purpose civil and commercialOfficial statements highlight uses such as the development of marine resources, deep-sea mining, the construction and repair of underwater oil and gas pipelines, and the maintenance of other infrastructure on the ocean floor.
These applications are perfectly plausible. A compact and reliable system that can cut damaged pipes, remove deformed segments, or maneuvering valves and flanges at great depths It's pure gold for the offshore energy industry. It reduces intervention times, decreases the need to send divers into hazardous environments, and lowers maintenance costs, which typically amount to millions per day of specialized vessel time at sea.
In deep-sea mining, where polymetallic nodules and other seabed resources are beginning to be explored, the capacity to install, cut and reposition structures In the abyssal zone, it is key to making large-scale projects viable. The same applies to more advanced engineering works, such as long-duration scientific stations, seismic observatories, or CO2 capture platforms in the seabed.
In fact, the previous experience of Chinese engineers cutting large-diameter pipes at 600 meters and carrying out repairs in less than half an hour is a compelling argument in favor of the industrial efficiency of this technologyIt is undeniable that, from a purely technical point of view, this is a very significant leap forward in subsea engineering.
The problem is that, in the current context, the line between an advanced maintenance tool and a sabotage weapon is extremely thin. The same saw that repairs a damaged pipeline in a gas field could, in another scenario, to take a key data cable out of service for the communications of an entire country.
Geopolitical dimension: from Taiwan to Brazil, via the Pacific
The strategic interpretation of this test was immediate. Taiwan, already concerned about the fragility of its 24 cables and incidents with Chinese ships, has seen its defenses reinforced. the fear that their connectivity could be "strangled" In a crisis scenario, for a territory whose economy relies heavily on the export of chips and technological services, a data blackout would be a devastating blow.
In Washington, the reaction was also swift. Analysts and US defense officials consider this EHA a system of dual use with direct military potentialThis is especially relevant in the Western Pacific. Cables connecting bases on strategic islands like Guam, or lines linking the United States with Asian allies, pass through depths where the Chinese device could theoretically operate without major difficulties.
In Europe, the test fits into a broader picture of concern about the safety of critical underwater infrastructure. The European Union and several member states have long been strengthening their policies to protect it. gas pipelines, oil pipelines and cablesEspecially after incidents in the North Sea and the Baltic. The idea that a rival power could operate silently at 3.500 meters is driving the acceleration of surveillance, redundancy, and rapid response plans.
A particularly illustrative case is that of Brazil. The country has at least 16 submarine cable systems Connected to its coast, with key arrival points in Fortaleza, Praia Grande, Santos, Rio de Janeiro, Salvador, and Recife, these lines link Brazil with the United States, Europe, Africa, and other South American countries, supporting both general internet traffic and financial and business communications.
Among these systems, the following stand out: Ella Link, which links Fortaleza with Sines (Portugal) and was built in part as a response to the NSA spying scandals; the BAGS, which connects Fortaleza with Luanda (Angola); the Firmine, powered by Google; and the SAILThe cable, which links Fortaleza with Cameroon and is partially operated by the Chinese state-owned company China Unicom, is a cause for concern for Brazilian analysts. The fact that China has demonstrated its ability to cut any cable at a depth of 3.500 meters using an underwater drone, while one of the routes connecting Brazil to the world is controlled by a Chinese company, is more than justifiable.
Risks to the digital economy and financial markets
From the perspective of investors and large technology corporations, what this test reveals is that The physical layer of the Internet is an operational risk in itself.And not just a neutral platform on which services are built. Until now, most security efforts have focused on cyberspace: firewalls, encryption, intrusion detection, access policies, etc. But a drone with a well-placed wire cutter can cause massive damage without needing to touch a single line of code.
The possibility of a "physical internet shutdown" is more than just a sensational headline. An attack that severs multiple cables at strategic points could disrupt real-time financial data flowsaffecting high-frequency trading, slowing down or crashing cloud services, cutting off military and emergency communications, and sowing chaos in markets that depend on constant, synchronized information.
Repairing a cable in deep water is slow and expensive: it can cost tens of millions of dollars and take weeks, even with good weather and available ships. Meanwhile, traffic must be rerouted along alternative routes that don't always have sufficient capacity, resulting in higher latencies, congestion, and service degradationFor regions with little redundancy—or for critical corridors like the Red Sea and the Strait of Hormuz, where incidents have already occurred and where insurers are becoming reluctant—the impact can be devastating.
Furthermore, the ability of China (or any other power developing similar systems) to repair faster than its rivals This also has implications. Whoever controls the ships, equipment, and access routes to the points of failure can gain influence over cable consortiums, negotiate advantageous terms, and, in critical situations, prioritize their own connectivity interests over those of third parties.
From technical protection to political and legal response
From a legal standpoint, things are not exactly clear. Current international law offers a Limited protection for submarine cablesespecially in international waters. Although agreements and conventions exist that prohibit their deliberate destruction, the actual ability to attribute a cut to a specific actor and to demand accountability is limited, especially if the attack is carried out in deep waters using discreet technologies.
The emergence of tools like this Chinese EHA opens the door to a new race to defend underwater infrastructureGovernments and operators may be forced to invest in near real-time monitoring systems of critical routes, sensors distributed on the seabed, surveillance drones, and urgent response protocols to detect and mitigate physical attacks, not just cyber ones.
At the same time, pressure is mounting to update international standards governing the use of underwater intervention equipment. There is already talk of the need for codes of conduct, transparency agreements and verification mechanisms that limit the malicious use of technologies capable of affecting critical infrastructure. It won't be easy, because these are dual-use capabilities with enormous civilian appeal, but the debate is already underway in specialized forums.
All of this is happening at a time when the The ocean floor has become an arena of strategic competition for energy, data, and mineral resources. The combination of regional tensions, advances in submarine engineering, and a regulatory vacuum is, at the very least, unstable. And each new demonstration of technological power—like that of the Haiyang Dizhi 2—adds another layer of complexity.
Overall, the test of the Chinese electrohydrostatic actuator does not spell the end of the digital world as we know it, but it does mark an uncomfortable turning pointThe security of the network economy is no longer solely at stake in data centers, firewalls, and cryptography, but also in a tangled web of fiber optics snaking along the ocean floor. From now on, any serious digital resilience strategy will have to consider not only bits and software, but also diamond saws and drones that can cripple the network that connects us all in a matter of minutes.
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