How do you know your super-quiet sub is undetectable by the most likely adversary? You send in the super-quiet sub on a series of probes, each time getting clo

How do you know your super-quiet sub is undetectable by the most likely adversary? You send in the super-quiet sub on a series of probes, each time getting closer, until there's contact and possibly an incident. Now you know how good the adversary is!