Is SSN(X) the right boat to comprise the future submarine fleet? Here's What You Need to Know: Block the straits between the islands and you imprison Chinese shipping within the China seas, doing the adversary a world of hurt in not just the military but the economic sphere. It doesn’t take a Seawolf-like submarine that sorties thousands of miles from home to seal off a narrow sea. A diesel sub stationed in the theater—at, say, Sasebo or Yokosuka, home to the U.S. Seventh Fleet—can reach its operating grounds and loiter there, sinking ships without all the excess capability manifest in an SSN.