For the first time since the end of the Cold War, the United States faces a resurgent submarine challenge from a state that is seeking to challenge American pre-eminence in Asia, and likely beyond. China is making a large-scale investment in the building up and sustaining of its submarine force, along with impressive investments in submarine weapons, surface warship, combat aircraft and space assets to complement its submarine force. Since the early World War II Battle of the Atlantic, when Germany's relatively small SSK fleet nearly knocked the U.S. out of the war, the U.S. has never let its strategic interests be so threatened by a foreign submarine fleet.

http://www.armedforcesjournal.com/2006/03/1813965