(Bloomberg) -- Subsea cables are the arteries of the internet, transmitting data between continents and underpinning an increasingly digital economy.
The cables are made up of tightly packed fiber-optic lines encased in layers of tough plastic or steel wire. When they break, it’s usually an accident caused by fishing trawlers or anchors dragging along the ocean floor.
Occasionally, it’s sabotage: an act of vandalism or an attack orchestrated by a government for the purpose of hybrid warfare.
Two fiber-optic cables were severed in the Baltic Sea in mid-November, one of them connecting Finland to Germany, the other linking Lithuania and Sweden. While the cause wasn’t immediately determined, governments in the region suspected the damage was deliberate.
How important are undersea internet cables?
They’re the conduit that allows people to send emails, post photos to social media, have video chats, make payments, stream movies and access artificial intelligence services such as ChatGPT.
Businesses and governments rely on them for communications, providing public services, payments, supply chain management and much else besides.
New satellite-based internet services such as Elon Musk’s Starlink are growing fast, but more than 95% of global data traffic still goes through subsea cables, according to the International Cable Protection Committee.
Whose job is it to protect subsea cables?
The owners of the cables are responsible for maintaining and securing the networks — telecommunications companies or, increasingly, big technology firms such as Alphabet Inc.’s Google and Meta Platforms Inc.
Many of those companies are American, giving a sense of security to the US and its allies that may be concerned about the risk of unfriendly nations tapping the cables to intercept sensitive communications.
To minimize disruption caused by cable faults, they often install more than one cable along a route or cut deals with other cable owners to provide back-up capacity.
If a cable goes offline, its owners and the companies that rent space on the cable can usually shift traffic onto another cable relatively easily, and summon a cable ship to investigate and make repairs.
If evidence points to deliberate damage, either because of suspicious activity of vessels in the area or the way the cable was cut, law enforcement and national security agencies will get involved.
What are the vulnerabilities?
Modern cables, most of which are about as thick as a garden hose, are typically buried under the seabed when they are installed. But shifting tides can bring them to the sea floor, where they are more vulnerable to being snagged — typically by anchors or fishing equipment.
The risk of damage is greatest along shipping routes such as the Red Sea and the Malacca Strait, where there’s a high concentration of cables in relatively shallow water, making accidents more likely.
Island nations or places with limited connectivity have most to lose when a cable is damaged, as a single fault can cut internet services entirely.
While sabotage at sea is possible, it’s easier to locate and potentially tamper with cables at landing points, where they connect with terrestrial infrastructure. These sites are often highly secure facilities.
How often do cables get damaged?
There are about 200 cable faults every year and the majority are caused by fishing activity such as trawling, in which heavy equipment scrapes the sea floor, or by ships’ anchors, according to data collected by the International Cable Protection Committee.
Shetland Islanders lost internet and phone services and shops couldn’t take credit card payments for a day after a fishing trawler damaged a cable in October 2022.
In March, the anchor of the cargo ship Rubymar severed three internet cables in the Red Sea after being struck by a Houthi missile.
Seismic events such as underwater earthquakes and rockslides can also take out cables.
An earthquake took out several West African cables in March, severely disrupting internet connectivity in several countries including Ivory Coast, Liberia and Benin. The outages created a capacity crunch in the region and took weeks to fix as telecom service providers scrambled to find alternative links.
Very rarely, nation states are accused of deliberately damaging subsea cables, although proving that they did so can be difficult.
What do we know about the cable incidents in the Baltic?
Investigators in Estonia, Finland and Sweden suspected that damage to two cables by a Hong Kong-flagged ship’s anchor in the Baltic Sea in 2023 was sabotage. The ship was accompanied by a Russian icebreaker and had only stopped at Russian ports since sailing from China a month earlier. No conclusive results of investigations into those events have been made public.
After the November 2024 cable severing incident, Danish Armed Forces followed a Chinese ship in the Baltic Sea. German Defense Minister Boris Pistorius said the damage had to be investigated as an act of sabotage, and pointed to Russia as posing a hybrid and military threat to the European Union.
What’s being done about subsea cable security?
Cable owners are focused on building out extra capacity to reduce reliance on single cables. They also give out maps of their cable routes to fishing companies and monitor the movement of boats using satellite imagery and vessel tracking signals, in some cases issuing warnings to vessels that get too close.
Government agencies have also been playing a bigger role in cable protection. The US military closely monitors shipping activity near cables and pipelines. Ten countries in Europe have partnered to track activity in the Baltic and North Sea, including deploying warships to patrol for would-be saboteurs.
©2024 Bloomberg L.P.