The missile silos and control facilities are connected in a sort of semi-mesh topology, so any one cable break is unlikely to cause a communications failure. There are backup launch control interfaces available via airborne platforms (specifically the E-6 today) as well.

Digging into one of the cables is going to get you a prompt and unpleasant visit from base security.

Image showing the layout/redundancy of the communications:

https://en.m.wikipedia.org/wiki/LGM-30_Minuteman#/media/File...

There are alternate ways to launch the missiles (e.g. radio from a plane) in the event of an attack.

They have redundancy. But they obviously want to know where it happened in case it was sabotage.