Attack Subs (White Giant)

Go the trade-products link. Order a Navy fleet command ship and a bunch of attack destroyers.

Once the unit shows up click on it and change the name to "Oskar class attack subs". Then you can shoot torpedoes at whatever you want.

I think the point here is that nuclear attack subs are very expensive and very deadly. They are not meant to be bought in thousands but in much smaller numbers. To act as carrier killers or SSBN hunters. Virtually undectable until they fire their weapons.