The problem with today's interconnected world is that a state actor bent on causing mischief could easily take a huge chunk out of global GDP by attacking infrastructure. We've already seen that such an actor can take out submarine oil pipelines and leave everybody in the dark about who really did it. (Although I suspect that state intelligence players quietly know for certain that it was Russia.)

An attack on submarine communications networks could be devastating. Europe, for instance, is woefully dependent on Internet access for almost all industry sectors. Cutting the lines across the Atlantic would bring entire sectors to a standstill, probably for months or years. Even allowing for my pessimism and industry's innovation it would be a huge blow.