We don't need submarines for that, a frigate with a 3" cannon can handle those on the water and an armed militia can handle those that already infest our shores.
A logical defence strategy for us cannot be to overpower China, but to inflict enough pain that less direct approaches would be preferred. We must counter them as well.
Note: I use China as a possible enemy but during the life of these subs other nations may have a resurgence.
