One of course is to use a much smaller EMP device to wipeout say Wall St. Another way is via a cyber attack shutting down servers and digital switches, in effect a virtual EMP. Yet sometimes in the age of blockbuster movies filled with tremendous explosions, we tend to predict apocalyptic scenarios when sometimes a good old-fashioned hammer works just as well.
According to the New York Times, the Russians may have been practicing their hammer swings. Russian subs seem to be paying a lot of attention to US data cables that stretch across the oceans. A well-aimed torpedo attack, or several well placed explosive charges, could do what the doomsday predictors have been imagining…a blinded and crippled US.
Russian subs have always been hard to detect and track. Attack subs could either fire torpedoes at the cables or divers could place charges on the cables (if that hasn't already happened). In either case, there would be no warning before the cables were cut. Even in the age of cellular phones, much of the data still travels through fiber optic cables. Taking out major networks with a physical attack is something that can't be easily countered.
Fiber optic cables also crisscross most of the US, traversing some very remote real estate. A few well timed attacks on these cables could also render the US blind.
The take-away from all of this is we need to stop thinking that the next attack will resemble anything we have seen before. It may be terrorists, Russians, Chinese or someone we've never heard of before. But out dependence on digital communications, and its relative softness compared to other high-value targets, makes this a very likely scenario. It also means that cyber attacks and hackers aren't the only threat, physical (or what military planners like to call kinetic) attacks require much less technical skill but are equally effective.