But low altitude? I'd consider that, say, 5 km or even less; why a hypersonic missile would be low-flying cruise missile? Why confront that awful aerodynamic drag?
Mainly for exactly the reason of making the missile too difficult to detect until it's far too late to do anything about it.
IIRC there's also two additional reasons: striking from a low angle means a better chance of damaging the ship at or below the waterline in order to sink it, and because sea-skimming means the sensors have a much easier time picking out the ship from the sea.
I mean, the aerodynamic drag is going to be forbidding high. One can't today make a low flying 20M cruise missile, no such technologies by a long shot.
Mainly for exactly the reason of making the missile too difficult to detect until it's far too late to do anything about it.
IIRC there's also two additional reasons: striking from a low angle means a better chance of damaging the ship at or below the waterline in order to sink it, and because sea-skimming means the sensors have a much easier time picking out the ship from the sea.