> Undersea cables are probably more expensive than satellites today, but we'll still continue to put them in. And nope, someone can't just walk in and cut a cable sitting at 5000m under the surface.

The cable has to come out on to the surface somewhere, though.

But barring that, dropping IEDs from a fishing boat, with a time fuse and some weight, isn't hard; the trickier part would be knowing where to drop them so they land near the cable. But there are tricks for that too.

Of course. But to Russias recent chagrin, blowing up/severing a fixed and very expensive cable (or underwater pipeline) is a generally far easier proposition than tracking down mobile and intermittent sources on the ground.

Still possible. But orders of magnitude harder. Nothing says that starlink ground station needs to stay in one place, after all.

Undersea cables get cut all the time, from shipping to nation states.

Trains don’t make cars obsolete, anymore than cars make trains obsolete. Taking out train tracks is much easier and more effective than taking out all possible roads though.