EXPERT PERSPECTIVE — When we think about the arteries of global power, images of oil pipelines or shipping lanes often come to mind. They are visible, tangible, and easy to picture on a map. The digital world has its own arteries, equally vital but far less visible: undersea cables, satellites, and semiconductor supply chains. These systems allow our economies to function, our militaries to coordinate, and our societies to remain connected.

We rarely stop to consider how very fragile they are. A fiber-optic cable lying quietly on the seabed, a satellite orbiting high above, or a single Dutch firm making the machines that build the world’s most advanced chips? Each represents a potential point of failure. And when one of them falters, whether by accident or design, the consequences ripple instantly across the globe. What makes this even more concerning is that adversaries understand their potential value. They have studied the geography of our digital world with the same intensity that past powers studied maritime routes. Increasingly, they are testing ways to hold these chokepoints at risk, not in open war, but in the murky space called the gray zone.

Consider the seabed. Nearly all intercontinental internet traffic runs not through satellites, as many imagine, but along the ocean floor. The “cloud” is, in truth, anchored to the seabed. These cables are resilient in some respects, yet highly vulnerable in others. Russia has long deployed specialized vessels (such as the Yantar) to loiter near critical routes, mapping them and raising concerns about sabotage. The People’s Republic of China has taken subtler approaches. On several occasions, cables linking Taiwan’s outlying islands have been cut by Chinese vessels in incidents they described as accidental. Taipei viewed them, by contrast, as deliberate acts of pressure that left communities offline for weeks.

Nature has been no less disruptive. A volcanic eruption severed Tonga’s only international cable in 2022, cutting off connectivity entirely. A landslide off Côte d’Ivoire in 2024 damaged four cables at once, leaving more than a dozen African states scrambling to restore service. These episodes remind us that chokepoints need not be destroyed to reveal their importance.

For China, the issue is a strategic one. Through its Digital Silk Road initiative, Beijing has financed and built cables across Asia, Africa, and Europe. Chinese firms now sit at landing stations and repair depots. In times of peace these investments look like connectivity. In times of crisis, they can become instruments of leverage or coercion.

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The same logic applies in orbit. Satellites and global navigation systems act as the nervous system of modern life. They time banking transactions, guide aircraft, and support military operations. Disrupting them unsettles the rhythms of daily existence. Russia previewed this dynamic in 2022 when it launched a cyberattack against the Viasat KA-SAT network on the first day of its invasion of Ukraine. Thousands of modems across Europe went dark, cutting off critical communications. More routinely, Russian jamming and spoofing around Kaliningrad and Moscow have disoriented navigation systems, with civilian pilots suddenly reporting the loss of GPS mid-flight.

China has created its own path through BeiDou, a rival to GPS that is already woven into infrastructure and commerce across large swaths of the world. Countries adopting BeiDou for civilian uses also create dependencies that, in a crisis, could become channels of influence. China’s so-called inspector satellites, capable of shadowing Western systems in orbit, serve as a reminder that the domain is contested and difficult to police. Jamming, spoofing, or orbital surveillance are rarely attributable in real time. They can be dismissed as interference or technical glitches even when deliberate. That ambiguity is precisely what makes them effective tools of gray-zone leverage.

Vulnerability also extends to the factories that produce the silicon chips powering the digital age. No chokepoint illustrates fragility more starkly than semiconductors. Advanced chips are the foundation of artificial intelligence, modern weapons systems, consumer electronics, modern automobiles, and more. Yet their production is concentrated in very few hands. One company in Taiwan manufactures most of the world’s leading-edge chips. A single Dutch firm produces the extreme ultraviolet lithography machines needed to make them. And China has demonstrated repeatedly how control over upstream minerals can be wielded as leverage. Restrictions on gallium, germanium, and graphite have caused immediate price spikes and sent Western companies scrambling for alternatives.

The global chip shortage during the pandemic provided a glimpse of how disruption can have cascading impacts. Automotive plants shut down, electronics prices soared, and entire supply chains stalled. That was the result of market forces. In a geopolitical crisis, disruption would be intentional, targeted, and likely more devastating.

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None of these vulnerabilities exist in isolation. Together, they form part of a broader and comprehensive strategy, particularly for China, where digital infrastructure has become a deliberate instrument of national power. Through the Digital Silk Road, through export controls on critical minerals, through investments in semiconductor capacity, through an ambitious national AI strategy, and BeiDou’s global adoption, Beijing is systematically building positions of leverage.

Is this preparation for an open assault on global systems? Maybe not, but it is a strategy designed for options in the gray zone. By holding digital chokepoints at risk, China can complicate allied decision-making and cast doubt on the reliability of critical systems, thereby slowing or obstructing responses at moments when speed is decisive. The ambiguity of each incident – whether it appears to be an accident, a policy choice, or something more calculated – becomes a tool of coercion.

The reality is that these risks cannot be eliminated. The very efficiency of the digital age depends on concentration. A single company leads in chipmaking, a limited set of satellites provides global timing, and relatively few cables carry the world’s data vast distances across the open ocean. Efficiency brings tremendous capability, but it also brings fragility. And fragility invites exploitation.

The counterweight must be resilience. That means redundant routes and suppliers, pre-positioned repair capacity, diversified supply chains, hardened infrastructure, and rehearsed recovery plans. The point is to recover and regain capacity as quickly as possible. To do so requires deeper public-private partnerships and closer coordination among allies, since no nation can protect these domains on its own. Resilience is not a one-time investment but a cultural shift. A culture that assumes disruption will come, prepares for it, and ensures that no single outage or shortage can paralyze us.

History offers some perspective. Nations once fought to control straits, canals, and oil fields. They still do so today, but increasingly our chokepoints are digital, hidden from sight yet just as consequential. Whoever shapes them, shapes the balance of global power.

Global stability today depends on foundations that are often invisible. Fiber-optic cables under the sea, satellites crossing the skies, and factories producing chips with microscopic precision form the backbone of our digital age. They showcase human ingenuity while highlighting profound vulnerabilities. Recognizing the duality of innovation’s promise alongside its fragility may be the most important step toward protecting what matters most in the digital age. And, yes, we must defend these technologies. But it’s about something bigger. It’s about ensuring that the digital world we depend on remains a source of strength, and not a lever of coercion.

All statements of fact, opinion, or analysis expressed are those of the author and do not reflect the official positions or views of the U.S. Government. Nothing in the contents should be construed as asserting or implying U.S. Government authentication of information or endorsement of the author's views.

The Cipher Brief is committed to publishing a range of perspectives on national security issues submitted by deeply experienced national security professionals.

Opinions expressed are those of the author and do not represent the views or opinions of The Cipher Brief.

Have a perspective to share based on your experience in the national security field? Send it to Editor@thecipherbrief.com for publication consideration.

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EXPERT Q&A — Reports of damage to undersea cables across the world are on the rise, with suspected foul play in many of these incidents. These cables are crucial conduits for communications, financial transactions, Internet traffic and even intelligence, making them prime targets of gray zone tactics, from suspected Russian sabotage of Baltic Sea cables to alleged Chinese severing of cables in the Taiwan Strait. The Federal Communications Commission voted last Thursday to update U.S. rules on subsea cable development, aiming to streamline construction and better protect this critical undersea infrastructure.

The Cipher Brief spoke with Rear Admiral (Ret.) Mike Studeman, who served as Commander of the Office of Naval Intelligence, about what he says is an ongoing assault on undersea cables — including “outside-in” attacks like sabotage and “inside-out” attacks from embedded exploits — and how the U.S. and its allies can better defend the cables they rely on. Our conversation has been edited for length and clarity.

The Cipher Brief: What is the perceived danger that we're talking about here that the Congress is perhaps seeking to address?

RADM Studeman: It's very clear that the adversaries of the United States, the Chinas and the Russias of the world, are very keen on trying to get leverage in various ways against the United States and the West through critical infrastructure. The subsea cables are just one element of critical infrastructure.

But frankly, the statistics would blow people's minds. Ninety-nine percent of our Internet traffic goes through the undersea environment. When you think about the capacity of those cables, it's terabytes of information versus gigabytes of information through satellites. So essentially, when you go through satellites, it's like drinking a glass of water in terms of the amount of data throughput you get. But undersea cables, it's like trying to drink a large swimming pool worth of data. So we're highly dependent on those. $22 trillion of financial transactions are processed through undersea cables every day. We also have our defense, our national security, our intelligence riding those cables like everybody else with their streaming videos and emails and all the rest. So the threat there is significant, just like it would be on land-based sites with people trying to get into your communications, manipulate them, outright disrupt them through severing and cutting.

The Cipher Brief: The implication of the request made by the House would appear that this is less of a concern about the severing and cutting of cables, but more that Chinese companies, particularly the maintenance and repair companies, may be getting access to these cables,and then doing what? Is it tapping? What are we talking about here?

RADM Studeman: There's the outside-in and then the inside-out threats and it's worth bifurcating it in the beginning. So if you're talking about the six sea cables that were more than likely purposely cut by Russia and China since November 2024 in the Baltics and the Taiwan Strait, it shows you what can happen. Now there are natural ways cables get cut; 150 to 200 times each year cables are damaged by underwater volcanoes, dredging, fishing vessels accidentally dragging their anchors. But these are more purposeful nation state threats that we're seeing that are emerging. So there's no doubt about the outside-in, which means we got to track suspicious vessels.

But the inside out threat is just as significant and we need to be mindful of it. There's a lot of different equipment that can be at the terminal landing sites in between the subsea segments from optical repeaters to other junction points on sea cables that could potentially have malware in them that could perform a variety of functions when directed. So part of it is about espionage and the ability to shunt information into a place where Chinese and Russian intelligence can go through it, even if it's encrypted. They're hoping that later on with decryption capabilities they are working on that they could end up having all this data that they can back cast and decrypt to learn all sorts of secrets. So there's the shunting and the access to data. And there's also the ability to potentially exploit and disrupt from the inside with whatever functionality exists anywhere along the full length of those cables.

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The Cipher Brief: How easy is it to say, we're not going to use those repair companies because they're associated with China, and we're just going to pivot and do it ourselves or figure out some other way? Is that something that can be changed on a dime? How hard is that?

RADM Studeman: We'll have to ask Microsoft, Google, Meta, and some other companies that question because the extent to which they're dependent and whether or not they have alternate ways of providing those services is really known better to them. But the report that got this going in the first place was that Microsoft was using Chinese companies to be involved in some of the maintenance work here.

I think we're doing the right thing. I think that there are alternate companies that can in fact provide these services and we need to get really wise about this and then hold the companies accountable to the national security requirements, which are legitimate, that we need them to be cooperative in to be safer and frankly more resilient because our adversaries wouldn't hesitate to use some of these exploitation techniques in the future. We can't be naive about this.

The Cipher Brief: Is there any evidence to your knowledge that this is more than a concern at the moment? In other words, any evidence that China has gotten into that big data fire hose that comes into this country or anywhere else for nefarious purposes?

RADM Studeman: I think it's 100% safe to say that the Chinese have been grabbing big data from all forms of communication that traverse the earth, including a substantial amount of U.S. and allied data that they have sitting there, which has been examined by their intelligence services, and could in the future, if encryption is broken, depending on what level it is, potentially also be something that they can analyze and go through. This is not some kind of theoretical threat. This is trying to stop something that's underway.

The Cipher Brief: And other than getting American or non-Chinese entities to do that work at the bottom of the ocean floor on the maintenance and repair side, is there anything else that you think ought to be done to address the threat?

RADM Studeman: I do think that when it comes to the manufacture of some of these cables that they're going, and discussions already exist about this, to put sensors of various types on there. There are normal anomalies and then other anomalies that could indicate that somebody's up to no good. There's signal distortions, there could be latency delays, there could be some anomalies after work is done in a certain segment of your cables. All those things deserve to have more sensors and therefore more analysis and more awareness because then you will know how to act appropriately to nip something in the bud, ideally, or to stop it soon after you detect it. But many cables are essentially dumb cables; they don't have enough of that sensing capability. So the newer ones should incorporate that technology that exists today. It's not hard, although it drives up the expense a little bit.

When it comes to the inside-out too, I do think that there are probably some software types and analytics that you could run against the data that the sensors provide. There's a different kind of tailored, maybe agentic AI which could be focused in this area too, to make sure you're not chasing your tail with false alarms. Trying to distinguish something that's truly, legitimately a concern versus something environmental or endemic to the running of the cable system altogether.

And then of course, you've already talked about steps to take with regard to identifying suspicious vessels that may be operating over these cables that may be up to no good. How do you deter that or how do you respond to that?

I also think that in terms of some of the resiliency efforts, we're gonna need to have more essentially underwater flyers, underwater drones. If you think about the Chinese and the Russian deep sea programs that have intent to go after cables, you need to examine them to make sure there's not a box that's been laid on top of them. Having some regular patrols, the Baltic states are currently doing that at the sort of air and surface level. And they're thinking about the desire for the undersea. We need to have more essentially drone flyers that are cheap, that can fly over the most critical cables out there. That to me is also where the future is going with all of these dangers that exist.

Opinions expressed are those of the interviewee and do not represent the views or opinions of The Cipher Brief.

The Cipher Brief is committed to publishing a range of perspectives on national security issues submitted by deeply experienced national security professionals.

Have a perspective to share based on your experience in the national security field? Send it to Editor@thecipherbrief.com for publication consideration.

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EXPERT Q&A — There is increasing focus on the vulnerability of undersea cables — a critical infrastructure which is key to much of global communications. They have been damaged in various hotspots around the world, with some incidents pointing to nefarious actors. Another threat beyond physical damage is the potential for intrusions and tapping, especially when it comes to U.S.-linked cables and China. Central to this issue is the dominance of Chinese companies in making, maintaining or repairing the cables linked to the U.S. In July, the chairs of three House committees wrote to the CEOs of Google, Meta, Microsoft, and Amazon to report on how exposed cables are to China in this way.

The Cipher Brief spoke with Beth Sanner, former Deputy Director of National Intelligence at ODNI, to assess the Chinese threat to undersea cables and why it is so challenging for the U.S. to mitigate the risk. Our conversation has been edited for length and clarity.

The Cipher Brief: What is the worry here? What's the kind of nightmare scenario? Why is the Congress asking the tech companies to report back on these things?

Sanner: So much of our communications flows through these cables, including encrypted classified information. There is a lot of stuff that is important. Not all of it is classified, of course — just everyday materials from financial transactions or people's connections to the internet. So there are obviously multiple reasons why we should consider undersea cables as part of U.S. critical infrastructure. But that critical infrastructure, unlike most of what we talk about, isn't only in the United States. In fact, all of this is outside the United States, and not even all of that connects directly to the United States. The vulnerability is so global because we are sending financial transactions between the United States and Singapore, for example, or even for China.

The Cipher Brief: There's no shortage of issues where the same concerns apply in terms of China having a hand in areas of our lives that involve data capture and data collection. Here, it's very hard to see how A, one would know exactly where that Chinese hand is, and B, let's say one of these companies comes back and says, well, we think that maybe a Chinese entity does some maintenance work. I imagine it's pretty hard to suddenly shift gears for Meta or Google or the other companies to say, okay, we'll just suddenly have another maintenance company that isn't Chinese.

Sanner: Right, so let's break that down a little bit. First, the way that information flows over these lines, it's very hard to restrict where things go. The messaging traffic tends to go on the lines that have the least amount of resistance and the most efficiency. So, your data can be going almost anywhere.

And we know that the FCC is going to be meeting in August and considering, and I would wager that they are going to, banning any Chinese equipment in cables that connect to the United States. (Editor’s Note: On August 7, 2025 the FCC banned the use of equipment and services from Chinese companies on its “Covered List” and other agencies’ lists of entities deemed national security threats on any future undersea cables connecting to the U.S.)

That suggests to me that there might be a problem that we don't know about. Is there the use of Chinese components even inside the cables connecting to the United States? I can tell you all cables connecting to U.S. military installations around the world, that I know of, though there could be exceptions, I think are handled by the American company called Subcom, which is owned by Cerberus, which Steve Feinberg, the now Deputy Secretary of Defense, was the co-CEO of until very recently.

But we just heard that Microsoft, in their cloud computing, with the U.S. DOD is using Chinese engineers for part of the maintenance of the cloud. And so it makes you wonder, I suppose it's possible that people are doing stupid things like using pieces like switching devices. Those switching devices direct the transmission of the light, or they could shut it down. What if those components, just like components that we recently heard were embedded in solar panels in the grid in Texas, are transmitting back or somehow controlled by China? I don't know, this is beyond my engineering capability, but I would say that we might have a problem there.

And then the third problem I would say is that this idea of the repairs, because most cables that are cut are accidentally cut. But if we rely on China for repairs, then something can be inserted in that process to tap that particular cable. And that can go on then indefinitely.

The Cipher Brief: We were just talking about some of the reporting that some of the big think tanks have done, CSIS in particular, that suggests that whereas Chinese companies and entities are not the market leaders when it comes to the construction of these cables that are reaching U.S. shores, they have a big chunk of the market, two companies in particular, when it comes to repair work.

Back to the first question, from your intelligence community background, how worrisome is that?

Sanner: Well, that is the ability to insert a tap automatically. That's how it is done. So, any time a Chinese ship repair operation is happening by the company that's a subsidiary of Huawei or the other company, all of these companies report back to Beijing and certainly can be not even compelled, just told to do that mission. So I consider that an absolutely high risk.

Now, my understanding is that Cerberus and Subcom are beginning a fleet of repair ships. They have two ships in this fleet of cable repair ships, according to one article that I read in Reuters. That's all I know is open source, of course. And so I think the United States understands this weakness. But my understanding, too, is that those Chinese ships have repaired 25% of the cables that have been cut. So again, our information can be on lines that are outside of our ecosystem. And I will say that, in terms of the overarching issue here, this is a private sector endeavor, right? There are no government owned cable lines. Not really. This is a private sector deal. And so this is where public private partnership needs to work.

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The Cipher Brief: Your point about American companies now getting involved in the repair work, the House committee that looks at China and national security issues has been so aggressive in everything from TikTok to all these other things. Undersea cables have been around for a while. You would think it would not have taken this long to do what you just said, which is have American companies go out and do this if they're so worried about it. Any thoughts as to why?

Sanner: Somebody's got to pay for the contract to have it because I think we've just counted on the private sector to do this.

The Cipher Brief: And then the other question, are we at a stage now with this sort of thing that if the company has any ties to Beijing that one has to be worried about it?

Sanner: I do think that it's true that anything that's connected to China is bad. We know that China's inside our critical infrastructure in the United States, right? And they are there to pre-position themselves in case of war, or maybe even as a preemptive thing to prevent us from interfering in, for example, a Taiwan invasion.

So I would think that undersea cables are no different when it comes to the United States, but I think we have a broader issue of the potential of a concerted effort to cut cables around the world because there's very little we can do to prevent that except in very defined geographic areas. So NATO last year set up a working group focused on undersea cables and the protection of them. And they're working on developing systems like AI systems and remote sensing in order to monitor what's going on and also to use that sensing to track the particular ships that they think are problematic, either from the gray tankers or these cargo ships that they know are problematic. We would need to replicate that in the Pacific. And who is going to do that? We don't have a NATO in the Pacific.

And so I think that that is a real challenge for us down the line. We can't just think of this as a geographic problem that begins and ends with what connects to the United States. I keep seeing this. It's like, well, we don't care what happens in Ukraine or we don't care what happens, we're here in America. That just does not work anymore. Our geography is wonderful and it protects us from some things, but when it comes to cyber and space and undersea cables, communications, that is not enough. So we have to think globally.

Opinions expressed are those of the interviewee and do not represent the views or opinions of The Cipher Brief.

The Cipher Brief is committed to publishing a range of perspectives on national security issues submitted by deeply experienced national security professionals.

Have a perspective to share based on your experience in the national security field? Send it to Editor@thecipherbrief.com for publication consideration.

Read more expert-driven national security insights, perspective and analysis in The Cipher Brief

CIPHER BRIEF REPORTING — The Federal Communications Commission (FCC) and members of Congress are warning that China may be engaged in underwater espionage – accessing government and private-sector data that travel via the vast global network of undersea cables.

The FCC voted Thursday to accelerate the deployment of American-made submarine cable systems, and prohibit the use of technology manufactured in China in any subsea cables that reach the United States. And last month the chairs of three House committees wrote to the CEOs of Google, Meta, Microsoft, and Amazon, asking them to identify the extent to which the subsea cable systems they use are produced, maintained, or repaired by China-based firms.

In their letter to the big tech companies, the members of Congress called undersea cables “one of the most strategically significant, and increasingly vulnerable, components of the world’s digital infrastructure…powering not only global commerce and innovation but also the core operational systems of national security, intelligence, and defense,” and they warned that the cables could “become a backdoor for espionage, disruption, or exploitation of U.S. data and communications assets.”

More broadly, the undersea cable questions are the latest in a series of concerns about actions taken by Beijing to infiltrate American critical infrastructure, following cyberattacks and breaches of U.S. water systems, power grids and other networks.

“The Chinese have been grabbing big data from all forms of communication that traverse the earth, including a substantial amount of U.S. and allied data,” Rear Admiral (Ret.) Mike Studeman, a former Commander of the Office of Naval Intelligence, told The Cipher Brief. “This is not some kind of theoretical threat. This is trying to stop something that's underway.”

The potential infiltration of the undersea cable network is “a significant threat,” Nick Thompson, a former CIA paramilitary officer and Naval Special Warfare Development Group operator, told The Cipher Brief. “China has invested heavily in cable repair infrastructure, and combined with its constant nefarious maritime activity throughout the world, it’s logical to elevate the risks to the highest levels of [the U.S.] government.”

Sabotage and espionage on the ocean floor

As The Cipher Brief has reported, undersea cables have become a vast and largely unseen piece of critical global infrastructure. Roughly 650 cables cover more than 800,000 miles of ocean floor, carrying a staggering 98 percent of the world’s data – everything from e-mail traffic to military communications to an estimated $22 trillion in financial transactions processed every day.

“When you think about the capacity of those cables, it's terabytes of information versus gigabytes of information through satellites,” Rear Adm. Studeman said. “When you go through satellites, it's like drinking a glass of water in terms of the amount of data throughput. But undersea cables, it's like trying to drink a large swimming pool worth of data. And so the threat is significant…people trying to get into your communications, manipulate them, or outright disrupt them through severing and cutting.”

The U.N. estimates that between 150-200 incidents of undersea cable damage occur each year, and while most are accidents involving dredging operations, dragged anchors, or natural disasters, cables have also been targeted by saboteurs, operating in what one report called the “gray zone of deniable attacks short of war.”

Russia and China have been accused of intentionally severing cables, particularly in the Baltic Sea and the waters near Taiwan. In one of the most widely-reported cases, Taiwan said that two submarine cables leading to its island of Matsu had been cut in 2023, causing widespread internet outages. Taiwan blamed two Chinese vessels for the damage, and officials in Taipei said they had documented 27 incidents since 2018 of Chinese vessels damaging undersea cables that served the island.

China and Russia have denied tampering with any undersea cables.

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The latest concerns are less about cutting cables, and more about the entities that manufacture and maintain the undersea network. More than 90 percent of the world’s subsea cables are manufactured and installed by four private firms: the American SubCom, France’s Alcatel Submarine Networks, Japan’s Nippon Electric Company and China’s HMN Technologies. According to a report by the Center for Strategic and International Studies (CSIS), HMN, formerly known as Huawei Marine Networks Co., Ltd., has been the world’s fastest-growing subsea cable builder over the past decade, and accounts for 18 % of the cables currently on the ocean floor.

HMN and the State-controlled Chinese firm S.B. Submarine Systems (SBSS) are also major players in the cable repair space – and they routinely underbid other companies for the repair work. According to CSIS, HMN Technologies’ bids for undersea cable projects are priced 20 to 30 percent lower than its rivals.

“If we rely on China for repairs, then something can be inserted in that process to tap that particular cable,” Beth Sanner, a former Deputy Director for National Intelligence at the ODNI, told The Cipher Brief. “Anytime a Chinese ship repair operation is happening…all of these companies report back to Beijing. So I consider that an absolutely high risk.”

Thompson noted that China offers an unparalleled suite of maintenance and repair services for the subsea cable networks – they have “available assets, they have the technical skill, and their services are much cheaper than Western companies,” he said. And the CSIS report warned of frequent repairs done by “high-risk vendors, some of whom are Chinese.” It found that “the overreliance on Chinese repair ships due to limited alternatives in the marketplace is another vulnerability…There are concerns that Chinese cable repair companies such as SBSS could tap undersea data streams.”

Erin Murphy, a Deputy Director at CSIS and expert on the undersea cable issue, likened the cable-repair issue to the questions any consumer might face when looking for a quick and effective fix.

“When you have a cable that needs to be repaired, you basically get in a queue to get a cable repair ship,” she told The Cipher Brief. “And sometimes it's Chinese. This doesn't mean that all Chinese ships are ready for espionage and ready for damage, but when there is a need to repair cables, you’ve got to go with the first-come, first-serve.”

Rear Adm. Studeman made the distinction between “outside-in” sabotage – the cable-cutting incidents – and “inside-out operations” that might be carried out in maintenance or repair work.

“The inside-out threat is just as significant and we need to be mindful of it,” Studeman said. Access to the cables, he said, allows U.S. adversaries to either capture data or sabotage the cables themselves.

“Part of it is about espionage and the ability to shunt information into a place where Chinese and Russian intelligence can go through it,” he said. “Even if it's encrypted, they're hoping that later on with decryption capabilities they are working on that they could end up having all this data that they can decrypt, and learn all sorts of secrets.”

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What to do about the problem?

The recent congressional requests of the four tech juggernauts are essentially a probe of their exposure to undersea espionage. The letters went to those four companies for a good reason: Amazon, Google, Meta, and Microsoft own or lease roughly half of all undersea bandwidth.

The committees asked the companies to submit detailed information on the subsea cable systems they use – the companies that manufacture and maintain them, and whether any China-linked “system elements” are used in the cables. The tech firms were also asked to provide lists of entities that had been contracted to work on the cables since Jan 1, 2018, information about how they monitor the traffic of foreign-flagged vessels near the cables, and “the physical and cyber safeguards put in place by each company to protect the cables during this maintenance or repair.”

The letters referenced Russia as well, but the focus was on China. The committees requested answers by August 4, and a briefing from each company by August 8, 2025.

After the deadlines passed, a source close to the committees would say only that the tech firms had responded and that “we have meetings set up” on the issue. The Cipher Brief reached out to Meta, Microsoft, Google and Amazon for comment but we have not heard back from them.

Whatever the companies report, experts are convinced of the risks, and many have offered potential solutions. One obvious remedy would involve turning to American companies to do the maintenance and repair work. Experts have called for growth in the Cable Security Fleet program, through which Congress has funded two privately-owned U.S. ships to repair hundreds of cables that reach the U.S.

Among other ideas: Build more cables. As CSIS’s Murphy said, “It comes down to a redundancy issue. The more cables that you lay…the more redundancy you build in.” Others have suggested establishing “a cable corridor,” in which critical cables are concentrated, meaning commercial vessels know to avoid the area, and monitoring is relatively easy. The drawback is that a malign actor would presumably learn about the location of “corridor” as well.

Rear Adm. Studeman and others have suggested the use of technology to upgrade the cable network, ensuring that more undersea cables are “smart,” and equipped with sonar to detect breaks easily. He suggested that sensors be placed in cables that would detect anomalies and “indicate that somebody's up to no good.” Such anomalies might include signal distortions, latency delays, and any hints that repair work had been done in a questionable manner.

“All those things deserve to have more sensors and therefore more analysis and more awareness,” Studeman said, “because then you will know how to act appropriately to nip something in the bud, or to stop it soon after you detect it.”

Ultimately, the concerns about infiltrating undersea cables amount to one more worry for national security officials who are already concerned that China has breached a range of critical systems in the U.S.

“We know that China's inside our critical infrastructure in the United States,” Sanner said. “And they are there to pre-position themselves in case of war, or maybe even as a preemptive thing to prevent us from interfering in, for example, a Taiwan invasion. So I would think that undersea cables are no different when it comes to the United States.”

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