Could an Attack on Undersea Cables Take Down the Internet?

undersea cable, disruption
Workers install an undersea fiber optic cable in Spain on June 13, 2017. Facebook and Microsoft have teamed up to run the cable from the U.S. to Spain, crossing under 4,100 miles (6,600 kilometers) of ocean. Ander Gillenea/AFP/Getty Images

Most of us probably don't realize it, but much of the infrastructure that makes the internet possible lies on the bottom of the world's oceans, in the form of vast networks of fiber-optic cables that transmit data between countries. (Here's a map of those connections.)

Despite the vital role that these cables play in global communications, they're largely unguarded because of their location underwater. That vulnerability is in the headlines lately, thanks to recent warnings from across the Atlantic that Russia could sabotage the cables and disrupt connections between the U.S. and Europe.


Recent Warnings

The head of the British defense establishment and chairman of NATO's military committee, Air Marshall Sir Stuart Peach, recently warned that cutting the cables "would immediately — and catastrophically — fracture both international trade and the internet," according to the Guardian.

Peach's warning echoed the conclusions of a 2017 report written by U.K. Member of Parliament Rishi Sunak, which described the potential for disruption of internet traffic as an "existential threat." Sunak noted that the cables, which are largely owned and operated by private companies, transmit $10 trillion in financial transfers each day.


It's not the first time that an alarm has been sounded about the undersea cable networks. This 2010 report written for the U.S. Department of Homeland Security, describes the effects of a 2008 incident in which three cables in the Mediterranean that connected Italy to Egypt were severed, apparently accidentally by commercial ships dragging their anchors. Eighty percent of the internet connectivity between Europe and the Middle East temporarily was lost. As a result, most of the U.S. Air Force's drone aircraft in Iraq were grounded, due to the lack of a reliable connection to technicians back in the U.S. "Cable breaks halfway across the world threaten U.S. vital national security interests," the report warned.

In 2015, The New York Times reported that a Russian spy ship, the Yantar, was kept under surveillance by U.S. planes, satellites and ships as it cruised slowly down the U.S. east coast, close to internet cables. The Russian ship reportedly was equipped with two miniature submarines capable of going into deep water to cut cables. Another Russian surveillance ship, the Viktor Leonov, was spotted off the coast of Delaware in February, according to the Christian Science Monitor.

But before you get too caught up in a nightmare scenario of the internet suddenly going dark due to sabotage, experts say the system — despite its lack of defenses — is resilient and would be difficult for an enemy nation or terrorist group to disable. The fiber cables that transmit the world's data are surprisingly slim, measuring less than 0.7 inches (17 millimeters) in thickness, according to Keith Schofield, general manager of the International Cable Protection Committee, a British-based industry group. But the fiber is encased in a hermetically sealed tube, which is in turn surrounded by layers of high-tensile steel wires, copper and polyethylene. For sections in shallower water, where cables are more likely to encounter ship anchors and other manmade hazards, additional layers of armor are sometimes added, or else cables are buried under the seabed, Schofield says in an email.

As a result, cables are damaged worldwide only about 200 times a year — "a tiny failure rate across a network of well over a million kilometers (621,000 miles) of cable linking people between continents," Schofield says.

It would be difficult to cut cables in the deep ocean, though a robotic submersible equipped with the right tools could pull it off, says Jim Hayes, president of the Fiber Optic Association, a California-based professional society that certifies cable network builders and operators, in a telephone interview. The cable networks are more vulnerable closer to land, where their connections are in shallower water and easier to reach. It wouldn't take a lot of sophisticated weapons or know-how to inflict the desired damage.

"If you want to interrupt communications, you hire a crappy old fishing trawler, give them a big anchor and tell them to drag it here," Hayes explains.


Location is Key

Attacking a cable landing probably wouldn't cause much disruption in the U.S. and other technologically advanced countries in Europe and East Asia, where there are a multitude of other connections that would keep the data flowing, Hayes said. "They might slow down the internet in New York City, but they're not going to disrupt it," he says. "There are other routes to get to the same place. They can just as easily go west around the world as go east. The internet works that way."

But sabotage could cause outages in a region such as the Middle East, where relatively few cables are bunched in places such as the Suez Canal and the Strait of Hormuz, Hayes says. Africa, where long stretches of the continent's coast are dependent upon one or two cables, also has higher vulnerability.


"Yes, you could disrupt the internet for a lengthy period, but only with certain attacks in certain places," Nicole Starosielski, an assistant professor of media, culture and communication at New York University and author of the 2015 book "The Undersea Network," explains in an email. "In others, traffic could be easily rerouted."

Hayes says that instead of cutting cables, the Russians might try breaking into them to intercept communications. A tapping device could be inserted into the cable and then linked to a transmitter on a buoy, which would upload the data to a satellite or to another cable close to shore, he says.


Frequently Answered Questions

Are there fiber optic cables in the ocean?
Yes, there are fiber optic cables in the ocean.