In some cases, these undersea cables literally stretch from one continent to another, and so it is impossible to guard them.  That means that they are an exceedingly vulnerable target, and it is probably just a matter of time before someone decides to attack them.  Of course if the undersea cables that connect one global superpower to the Internet get hit, they will probably start cutting key undersea cables that connect their enemies to the Internet.  Needless to say, such a scenario would have the potential to turn apocalyptic very rapidly.

According to CNN, U.S. officials are warning that there has been "increased Russian military activity around key undersea cables"…

The US has detected increased Russian military activity around key undersea cables, and believes Russia may now be more likely to carry out potential sabotage operations aimed at disabling a critical piece of the world's communications infrastructure, two US officials told CNN.

Russia has put increasing emphasis on building up a dedicated military unit, which deploys a formidable fleet of surface ships, submarines and naval drones, according to one of the officials. The unit, the "General Staff Main Directorate for Deep Sea Research," is known by its Russian acronym GUGI.

"We are concerned about heightened Russian naval activity worldwide and that Russia's decision calculus for damaging US and allied undersea critical infrastructure may be changing," a US official told CNN. "Russia is continuing to develop naval capabilities for undersea sabotage mainly thru GUGI, a closely guarded unit that operates surface vessels, submarines and naval drones."

On the other side, the Russians are suggesting that it is actually the U.S. and the U.K. that are preparing to start attacking undersea Internet cables…

An ally of Vladimir Putin has accused the U.S. and the U.K. of intending to sabotage underwater internet cables and planning to destabilize the maritime energy trade.