Joe Biden blew a wind of concern on the global cyber landscape on Monday, March 21.

"The Russian state is considering different possible avenues of cyberattacks," said the President of the United States, saying he was based on "constantly changing information". 

It is not the first time since the start of Russia's invasion of Ukraine that the US executive has warned of the threat of attacks orchestrated by hackers on orders from Moscow.

The day after the launch of the Russian offensive, Washington even said it was "ready" to ward off any Russian cyberattack.

>> To read also: Ukraine: Russia accused of having drawn the cyber weapon

More than 430 submarine cables threatened

But this time, Joe Biden urged American businesses to "shut down their digital doors" as soon as possible to protect themselves.

The "unprecedented cost inflicted on Russia" by the sanctions decided by the international community could push Moscow to take revenge on the West in cyberspace, concluded Joe Biden. 

In other words, Russian President Vladimir Putin, cornered by sanctions, would now be ready for war escalation by directly attacking NATO countries using cyber weapons.

Accusations that Moscow hastened to reject categorically.

"The Russian Federation, unlike many western countries, including the United States, does not engage in this kind of digital state banditry," Kremlin spokesman Dmitry Peskov said. .

But Joe Biden's warnings have nevertheless brought back to the media the specter of a digital catastrophe scenario which would see Russia deprive the whole world of the Internet by attacking the submarine cables of the Cloth.

This hypothesis has been raised more than once, even in high military circles since the beginning of the Ukrainian crisis.

In January 2022, Admiral Tony Radakin, head of the British armed forces, declared that Moscow could "endanger the system of information circulation which depends on the numerous submarine cables", recalls the Guardian.

A hypothesis shared by the very influential American think tank Atlantic Council, which published a summary, at the beginning of the year, devoted to this risk.

It must be said that the more than 430 submarine Internet cables represent tempting targets for anyone who wants to disrupt global connectivity.

Often considered one of the weak links in the global network, these cables "look like big garden hoses lying on the bottom of the sea", describes Tobias Liebetrau, specialist in international relations and computer security issues at the Danish Institute for International Studies.

Above all, they do not benefit from any particular protection, except "integrated surveillance systems which make it possible to alert if there is a threat nearby", continues this researcher who is the co-author of a study on the security of the submarine cable network published in the journal Contemporary Security Policy in 2021. 

Easy to hide attacks...

Helpless "victims" who are also rather easy to attack.

"It is theoretically very easy to conceal submarine cable sabotage," said Christian Bueger, also co-author of the article in the journal Contemporary Security Policy and specialist in maritime security issues at the University of Copenhagen, contacted by France. 24. 

It would be enough for a merchant ship or a fishing boat to drop anchor just above a submarine cable not far from the coast (where these infrastructures are not too deep) to damage it.

Divers or submarines can also come and place explosives on these cables or install nearby mines, which can then be triggered remotely.

Operations that seem easy for potentially spectacular and very costly results for Western economies.

As soon as a European Internet user connects to his Gmail inbox, writes a tweet or "likes" the message of a high school friend on Facebook, his requests cross the Atlantic through these submarine cables.

"They're vital if you're looking to transfer data to countries that don't have land connections to where you are," Emile Aben, IT security specialist at the RIPE Network Coordination Center, told France 24. NGO which serves as a regional register of IP addresses (addresses on the Internet network) for Europe and the Middle East in particular.

If the hypothesis of a Russian attack against these infrastructures is so worrying, it is partly "because there have been suspicious activities by Russia at sea near the places where these cables are located", recalls Christian Bueger .

Russian ships have thus carried out exercises not far from Ireland or Norway, where several submarine cables pass linking Europe to the United States.

Russian research boats were also spotted in 2014 off Portugal, again in an area where there are a dozen submarine cables.

For years, there has therefore been a suspicion that "Russia is preparing something", notes Christian Bueger.

… but difficult to implement

For this expert, there is also "the impression that during each conflict, the means of communication are always part of the priority targets. During the Second World War, it was the telegraphs, and today it would be the cables under sailors."

Except that depriving the world of the Internet is not as easy as making the means of telecommunication inaccessible by cutting electric wires on the front in 1939. "Attacking a cable is a bit like destroying a single track on a ten-lane highway", summarizes Emile Aben.

Highly connected countries, like most European states, the United States or Asian countries, have many more than one submarine cable to connect them to the world.

Precisely because these infrastructures are fragile.

"Apart from a few isolated islands, there are few countries that would be deprived of the Internet if only two or three cables were damaged", recognizes Tobias Liebetrau.

This would be the case for the Azores archipelago, the island of Madeira or the Australian state of Tasmania.

"Russia should therefore set up a large-scale military operation to really endanger Internet access for the United States or Europe," said Tobias Liebetrau.

It would first be necessary to carry out reconnaissance operations to know exactly where each cable is "because if maps exist, they are deliberately imprecise", notes this expert. 

Russia would then have to mobilize a significant number of ships and submarines to strike all the targeted cables simultaneously.

"The most effective would perhaps be a targeted operation in the Suez Canal, where a large part of the data circulating between Europe and Asia passes," said Christian Bueger. 

In addition, this kind of action would mainly cause harm to civilian populations.

"If there is no alternative to submarine cables in terms of daily use of the Internet [managing financial flows, watching films, playing video games], certain less data-intensive communications, such as military or government-to-government communications, could be supported by satellite networks," said Christian Bueger.

This is why, even if in theory the submarine cables appear as first choice targets, "it is very unlikely that this is an option chosen by Moscow", estimates Tobias Liebetrau.

Indeed, there is no doubt that this type of attack would be considered an act of war by the West.

This is what British Admiral Tony Radakin said.

And Moscow would probably not be prepared for such an escalation for an operation that would require a lot of resources without having a noticeable impact on NATO's military capabilities.

On the other hand, the Russians could attack one or two cables "to issue a symbolic warning", estimates Christian Bueger.

History to put the finger where it can hurt and demonstrate that they know how to do it.

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