What’s one piece of infrastructure that — more than anything else — forms the backbone of the modern world? It’s not roads, bridges or even 5G towers — it’s the internet cables that sit on the sea floor and span the globe.

These cables are essential for our globalized, connected world, facilitating trillions of dollars of transactions a day and carrying everything from WhatsApp messages to classified government information. Yet the protections for these cables under international law are confusing and, in many cases, antiquated.

They may also be some of the first things affected in a major conflict between global powers. According to a Reuters investigation, the U.S. and China are vying for influence over who gets to build and maintain cables. For more on all this, Marketplace’s Sabri Ben-Achour spoke with James Kraska, a professor of International Maritime Law at the U.S. Naval War College. Below is an edited transcript of their conversation.

Sabri Ben-Achour: The U.S. and China have been going through this behind-the-scenes battle and I mean, like, playing dirty over which companies, Chinese or American, should be laying these cables. And I’m gonna ask you about that in a second. But first, can you just remind us why undersea internet cables are so important to the global economy and basically modern life in general?

James Kraska: Yes, absolutely. These are the backbone for the global information system, the global information network, and they carry about 99% of all our telecommunications because satellite doesn’t have the bandwidth, and it costs too much. And so almost all of our communications — and this includes banking transactions, all of our internet activities — go via submarine cables. And because it’s a globalized world and the economy is interconnected, these have never been more important.

Ben-Achour: Well, so if there was some sort of international conflict or something, are there rules that protect these cables?

Kraska: Very minimal rules. The rules were developed during the era of copper cables, and they only pertain to connecting bilateral cables connecting one country to another country. And the problem today is that submarine cables are a fiber optic. They are constructed through a consortium of companies, and these consortia will sublease part of their bandwidth to even other companies. And so there’s no such thing really as a bilateral submarine cable that’s used by civilians today. It’s very difficult to find out sometimes who actually owns divisible rights or indivisible rights in the cable. And then it’s virtually impossible to know whether those companies have subleased their indivisible rights to other companies. Furthermore, all of these cables have both civilian traffic, as well as military traffic because the military traffic is encrypted, but it still goes on the same cables that we use every day for our internet.

Ben-Achour: If these cables were cut or damaged in wartime or some conflict, how bad would that be? And how hard or easy would it be to reconnect them?

Kraska: Well, it depends on how many cables are available, that is, how much redundancy exists. So if a single cable is cut to an area that has a number of cable landings, say the United States or Europe — all of that traffic is automatically rerouted. And it’s rerouted by computer in a millisecond. The problem will be in some areas that have fewer cable landing sites, particularly in the developing world or remote islands, in which case, if they’re only serviced by one or a small number of cables, then they could be, you know, virtually completely isolated. The other thing and this is that you’ll notice that Russia, for example, is a major land power. And so its communications, you can bet, are primarily internal lines of communications. The United States is a maritime power. And so it connects with its friends and allies around the world through submarine cables. And so it has somewhat more vulnerability in this regard.

Ben-Achour: In February, American subsea cable company SubCom started laying down a $600 million cable to transport data from Asia to Europe through African Middle East that was originally going to be done by a Chinese company that would have done it for cheaper. But the U.S. government intervened, told the backers of this project, including Google and Amazon, that you’re going to make no money on this because we are probably going to impose sanctions that would affect this deal. Talk about strong-arm tactics. Why is the U.S. playing hardball on this with China?

Kraska: Well, I mean, I’m not sure of the details in this case, but you can just think about submarine cables and how important that they are and how companies and countries that have access to all of the data that are going through the pipe and how that might have some sort of strategic or military value. And so I think this probably underscores the weariness that the United States has had with Chinese telecommunications and submarine cables. 

Ben-Achour: I mean, do you think these cables can be used for espionage or are being used for espionage?

Kraska: So I don’t have any sort of particular insight on this other than that all of the information that we use goes to these cables. So, you know, it just makes sense that they would have some type of value. I guess I would say that the proof would be in the capabilities. And the United States, as well as Russia and China, have in the open source certain capabilities that apparently are used to either repair or access or in some way interact with submarine cables. And so that, you know, leads one to think that there is a value of doing so.

Ben-Achour: Are these cables protected somehow? I mean, if there was a conflict, say between the U.S. and China, what would it mean if they weren’t protected?

Kraska: So submarine cables are protected in the Law of the Sea Convention, the UN Convention on the Law of the Sea, which is reflective of customary international law. The United States is not a party to the UN Convention on the Law of the Sea, but because it’s reflective of customary international law, the United States adheres to it and virtually every country in the world regards this treaty as a constitution for the world’s oceans. In Article 112 of that treaty, all states have the right to lay submarine cables on the deep seabed and on the continental shelf of other countries. And there is a liability regime in Article 115, where states can be indemnified for losses if a cable, for example, is cut. Usually, these are of course by accident, such as fishing vessels that drag an anchor across a cable. Now, that’s the peacetime regime or set of rules during armed conflict. There’s just not a lot of black letter law that applies except that in armed conflict, military objectives are lawful — maybe lawful — military targets. So any sort of attack or disruption on them has to be weighed against distinction. Are you attacking? Are you able to distinguish between a military target and a civilian target? And in this case, it’s sort of a dual-use item, dual-use infrastructure, and then proportionality. Even if it is a military target, is your attack disproportionate? And these are questions that have not been answered because we’ve not had much experience with cutting cables during armed conflict in the present day.

Ben-Achour: Yeah, it sounds like this is a major vulnerability.

Kraska: It is a major vulnerability. There’s a lot of disruption. But if you think of a country, for example, like China, it’s also much more connected to the globalized economy. Any type of disruption could reverberate follow-on effects. And so it’s one of these measures that might have just as much blowback effect on the country cutting the cable as it does on the country that that’s supposed to be targeted.