How does USN know which subs are NK?
Wouldn’t want to fire at the wrong countries subs.
US subs are listening to unique machinery sound and probably even norks speaking in nork gibberish inside the sub
I've spoken with some bubblehead Sonar techs who quite cheerfully claimed they could not only identify name/hull number/country of origin/date of launch and last refit, but tell you how many cups of coffee the galley had served and the color of the Captain's jockey shorts.
They may have been exaggerating about those jockey shorts, but not much else.