Yes, the cables going across the ocean do present a point of vulnerability for several thousand kilometres. I know that the U.S. has the capability of pulling up those cables and splicing in and intercepting. I wouldn't be surprised if the Russians and the Chinese do as well. One of the ways to get around that is through redundancy: You build over-capacity so that if one link goes down, you have others that are working. That is the case for at least one of the cables that land in Nova Scotia—the Hibernia cable. It's a sort of loop.
I think we need to invest in redundancy to minimize the number of critical points of failure, so that if there is an attack, it is much harder for everything to come down at once, and if one thing comes down, you can reroute around it. Unfortunately, the emphasis and imperative toward efficiency and speed means that very often there's a tendency to put too many eggs in a few baskets. I'd say a general approach to security is through redundancy and duplication—and that needs to be invested in. We need to be aware of that and not discover too late that when one thing goes down, everything goes down.
