Underwater internet cables could be the next target in tech warfare

Cross section of deep sea fiber-optic cable.
Cross section of deep sea fiber-optic cable.
Image: Illustration by Quartz, renderings by Wikimedia Commons and Southern Cross Cable
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Underlying the internet, often literally lying under the sea, is a surprisingly vulnerable array of cables that keep the world connected.

When we talk about modern tech warfare, we’re usually focused on nuclear reactors, water pumps, or transportation systems. We might think of the super-virus deployed by the United States and Israel to slow down Iran’s nuclear program in 2010. We don’t typically consider the miles of undersea cables that, according to the US Federal Reserve, carry $10 trillion in transactions every day.

Now, the US government is concerned the Russian military could attempt to sabotage these cables in a time of conflict, according to the New York Times (paywall). The newspaper reported an uptick of activity by Russian submarines near several major cables.

Although internet cables close to shore tend to be bulky and well-armored, those that run along the deep sea are often much thinner, according to Nicole Starosielski, a communications professor at New York University and author of The Undersea Network. These cables, like the one we’ve illustrated above, are just a centimeter or two in diameter and protected only by an outer layer of insulation.

Cables are generally safest out in the deep sea, but it’s not uncommon for them to be accidentally damaged by fishing operations. “An undersea grapnel could easily cut a cable, as can an anchor,” Starosielski wrote in an email. “It happens all the time.”

“It wouldn’t be much trouble at all” for the Russian military to deliberately sabotage such a cable, Starosielski said.

Damage to cables that are close to shore can be fixed fairly quickly. Not so for broken lines in the middle of the ocean. ”Since ships have to cross the ocean before getting to the line, this unavoidably takes time,” Starosielski said.

Still, undersea cable damage and repair is a regular practice, and most internet traffic to and from the US can travel over multiple routes, avoiding any cables that have been disabled. There would have to be a very specific moment within a very specific conflict for Russia to cut an internet cable and expect it to have a major impact.