What kind of resiliency are you hoping to achieve? For most routes, there are many dozens of cables starting at many different locations and taking many distinct paths across the ocean. The companies using these cables take great pains to ensure redundancy for critical paths: they'll validate minimum distances between the cables, ensure that they have a variety of landing points, ensure that they have enough spare capacity to handle a certain number of cables all being out for repair simultaneously. Alternatives to cables would be either land-based wireless (radio, point-to-point microwave) or satellite, both of which have much lower throughput capabilities and also are vulnerable to sabotage of transmission/receiver locations.

While the number of cables is not large enough to put it out of the reach of many nations, it's also something that no group with the capability of doing it would really want to do: it's a surefire way to invite retribution from basically the rest of the world, while not really achieving much militarily: armies almost invariably have their own communication systems (satellite, microwave, transoceanic fiber whose location is secret, etc).