Attacks on underseas cables have been common in previous wars

Submarine infrastructure is already vulnerable to attack and will become even more so in the coming years, especially as undersea vehicles grow more advanced and accessible. Unprotected cables and energy infrastructure could provide adversaries with all kinds of opportunities to gain the upper hand. Hostile forces could, for instance, plant explosive charges in sensitive locations and threaten to pull the trigger. Or they could set off explosions without warning, throwing markets into chaos and disrupting military command-and-control systems. State and nonstate actors could conduct anonymous attacks or act under a false flag. Attributing responsibility for a covert attack would prove challenging, making deterrence extremely difficult. Such moves wouldn’t be unprecedented, of course: before undersea fiber optics dominated global communications, cable cutting was a regular part of warfare. In 1914, the United Kingdom severed all five of Germany’s undersea cables in the English Channel the day after declaring war, and belligerents regularly snipped enemy cables during World War II. But today, it would be more difficult to sever fiber-optic lines without affecting a much larger and more interdependent system—making a potential attack all the more damaging.