Since November 2022, in the Baltic Sea, several telecommunications cables have undergone strange incidents. On November 18, the BCS East West Interlink line, connecting Lithuania to the Swedish island in Gotland was broken. The same day, a few hundred kilometers away, the C-Lion1 cable connecting Germany and Finland suffered damage. In December, it is the Eastlink 2 cable turn between Estonia and Finland, to be damaged. In January again, the LVRTC link, between Ventspil, in Latvia, and the island of Gotland, was cut.
Difficult to establish with certainty the causes of these damage. “There are nearly 200 cables cut per year, and in 80 % of cases, these are fishing accidents, anchors or landslides,” recalls Vincent Lemaire, vice-president at Alcatel Submarine Network (ASN). The German, Finnish, Estonian and Latvian authorities suspect, however, attempts to sabotage. Since the beginning of the invasion of Ukraine, tension has risen in the Baltic Sea, bordered on one side by members of NATO, on the other, by Russia accused of carrying out a “hybrid war”. Companies and governments therefore set up new means of protecting and monitoring cables.
“Armed” and buried cables
These spuns are a centerpiece of digital world architecture. “Today, 99 % of Intercontinental Internet traffic passes through these cables,” explains Stéphane Lelux, president of the Tactis consulting firm and expert in these submarine links. A real spine of the Internet, they make it possible to transmit data from one country to another, ensure the connections, and increase the speed of data circulation.
Promptly repaired, incidents in recent months in the Baltic Sea have not disrupted Europe. But the case of the Tonga Islands recalls that cuts can be heavy with consequences. In 2022, the cable connecting the country to the rest of the world had been torn during an underwater rash. These isolated islands of the Pacific had then been cut off from the Internet for almost a month, pending repairs.
Repeated incidents at the Baltic Sea make the safety of these cables a more pressing question than ever. The European Commission also presented in February a plan In several axes to strengthen cable protection. In particular, it plans to increase the means of detecting threats and to strengthen security requirements for these infrastructure. These submarine internet cables from 5 to 10 centimeters in diameter already have protective layers formed with thick metal wires – their hearts which shelters thin optical fibers occupies only 1.8 centimeter.
“When the seabed is more than 2,000 meters away, the cables are simply left on the ground,” explains Stéphane Lelux. But in shallow waters, it is necessary to “wake up” the cables: specialized boats dig furrows of one or two meters in which the cables are buried, in order to prevent anchors or fishing nets from accidentally coming to damage them.
In the Baltic Sea, despite an average depth of 55 meters, it is unfortunately not possible to use this technique. “Baltic soil is very damaged. There are many rocks and various seabed, with an alternation of sandy land and harder clays. It is a very difficult environment to dig,” explains Hugo Bouvy, general manager of the Deme Offshore group, specializing in the development of maritime infrastructure.
Baltic is, moreover, a huge boats cemetery. Nearly 100,000 wrecks, well preserved by these cold and little salty waters, would litter the funds. An impossible challenge for boats responsible for digging the furrows, which are not equipped to move or clear the wrecks. Baltic cables are therefore easy targets. A boat hanging out its anchor can easily damage one. It is also possible to place explosive loads on these cables, or to use an underwater drone equipped to cut them.
Looking for alternatives
Faced with these threats, the owners of these links seek to equip themselves too. ASN has thus developed Optodas, “an optical device that is injected on an optical fiber and which detects and locates vibrations close to the cable”, explains Vincent Lemaire. The device works as a kind of radar, allowing to know, thanks to vibrations, if trawlers, animals, or even drones are approaching. “The idea is to develop not a cable that would resist everything and that would cost fortunes, but rather remote surveillance solutions,” continues the expert.
It is with this in mind that “sea surveillance patrols with special buildings are starting to go into operation”, abounds Stéphane Lelux. In France, the Navy Cephismer cell specializes in surveillance missions. And the military programming law of 2024 has provided a budget of 300 million euros for the Caliope program, which should make it possible to intervene up to 6,000 meters deep in the event of incidents on strategic infrastructure, specifies the specialist.
At European level, the Seacure initiative, launched in November, aims to develop a defense system in the event of “underwater war” by 2028, and to ensure critical maritime infrastructures. Finally, the program Heist NATO, announced last summer, provides for the creation of a hybrid network – submarine cables and satellite communications – in order to ensure the resilience of the world’s internet in the event of a major incident.
“The best solution remains to multiply the number of cables. There are always at least three that exist in parallel,” recommends Michaël Trabbia, CEO of Orange Wholesale, the group’s infrastructure division. In fact, few countries take the risk of relying only on a connection. In mainland France, there are for example about thirty. And twenty-two submarine cables connect the ultramarine French territories. Disconnecting an entire country would therefore require a large -scale coordinated attack. Proof that the resilience of the Marche network, most Internet users never notice incidents, while it occurs on average between 150 and 200 each year.
.