IIRC, Clancy was approached by a Naval security officer after The Hunt for Red October was published asking him how he knew about certain things he had written about.
Clancy’s replied he learned of it from bits and pieces gleaned from published naval journals.
Yes, sometimes the Navy is sloppy in that way, but still, they don’t as a policy endorse or publicize overtly what their detection capabilities are. I might add that a lot of military personnel of different flavors liked his work and that it is possible that one or more of them personally filtered what they knew and didn’t do a very good job of it.
The urge to brag and divulge is sometimes strong with those loosely connected to things like this, and they think ‘talking in code or being nebulous’ is not divulging capabilities.