You are supposed to pull it up into the belly of the sub and open the skin up and reconnect the individual lines with your patches to the listening taps one by one, not sever it and let everyone know you are jacking around with it! They probably already know where the break is.
(I suppose it could just be something natural like volcanic lava or a giant kraken that severed it.)
https://www.websitepulse.com/blog/submarine-communication-lines
"The technology allowing cable problem detection is called Brillouin Optical Time Domain Reflectometry. This technology provides very high precision when detecting a cable fault. The video below visualizes how to repair operations are carried out" (see link for details!)
Yes, another “oops” moment. I like the giant Kraken theory.