Regional Sea Denial
Submarines can take the lead in establishing local sea superiority during a crisis.  Local sea superiority is necessary for all follow-on naval operations.  Submarines, being survivable, would eliminate enemy submarines and enemy surface ships which are armed with surface-to-surface and surface-to-air missiles.  Submarines could also plant mines to deny use of harbors, straits, and other sea areas.

The utility of submarines in this role will most likely be greatest in enemy coastal areas, where other U.S. forces may be at risk.

A prinicipal use of submarines in a regional conflict would be the early application of force to keep an adversary's maritime forces in port.

Submarines carry a variety of weapons for use against an enemy's surface ships and submarines.  The U.S. heavyweight homing torpedo is the most effective weapon against enemy submarines and surface ships.  Cruise missiles are also effective against surface ships and land targets.