in  positions  to  achieve  three  purposes.  First,  forces can engage the enemy promptly at the start of hostilities. Second, they can provide protection and support to friendly, allied, and U.S. forces in time of war. Third, they can stop the advance of the enemy as soon as possible. However, the positioning of these naval forces for warfare in sensitive  areas  of  the  world  also  provides  a  side benefit known as presence. Because of the inter- national  character  of  the  high  seas,  deployed  U.S. forces have a unique ability to make U.S. military presence known in a time of crisis. The United States  can  modify  that  presence  to  exert  the  degree and type of influence best suited to resolve the situation. A show of force by U.S. naval warships can restore stability to a friendly nation that is unable to  control  a  hostile  situation.  The  U.S.  fleet  can remain out of sight, over the horizon, ready to respond in a matter of minutes to any crisis. Naval presence can be visible or invisible, large or small, forceful  or  peaceful,  depending  on  what  best  suits U.S.  interests. Naval forces can remain in a crisis area for indefinite  periods  to  communicate  their  capability for action. Ground and air forces can duplicate that capability only by landing or entering the sovereign air space of another nation. We cannot consider the effectiveness of our naval presence separately from our warfare capability.  To  encourage  friends,  deter  enemies, or  influence  neutrals,  forces  deployed  to  crisis areas  must  possess  a  fighting  capability. Our  naval  presence  must  also  reflect  the  degree of U.S. interests in the area relative to the number of naval forces in the area. To be effective in the presence role, U.S. naval forces must reflect a ready  combat  capability  to  carry  out  their mission  against  ANY  implied  threat. THE  NAVY’S  WARTIME  MISSION Should  the  United  States  fail  in  its  peacetime efforts, the Navy must shift from a peacetime to a wartime posture. In its wartime posture, the Navy has two areas of responsibility. It must be able to function in a hostile environment, and it must be able to exercise sea control and power projection.  Sea  control  and  power  projection  are essential to our use of the seas to support our national policies. The concepts of sea control and power  projection  are  closely  interrelated.  A  naval force  must  have  some  degree  of  sea  control  in  the sea areas from which it is to project power, depending  on  the  type  of  force  to  be  used. However, a naval force must have the capability to project power before it can realize any degree of  sea  control. Sea Control Sea control is the basic function of the U.S. Navy.  It  involves  control  of  designated  air, surface, and subsurface areas. Sea control is of crucial importance to the U.S. strategy of using  both  oceans  as  barriers  for  defense  and as avenues to extend our influence overseas. It does not imply simultaneous control over all 70  percent  of  the  earth  covered  by  international waters;    it  is  a  selective  function,  exercised only when and where necessary. Because of new technology developed in the United States and in  other  countries,  total  control  of  the  seas for our use and the denial of the seas for the enemy’s use are impossible. With continuing technological  developments,  such  as  the  strategic defense initiative, total sea control is expected to  become  even  more  difficult. Sea control assures the buildup and resupply of  allied  forces  and  the  free  flow  of  needed supplies.  Sea  control  also  enhances  security  for the  nation’s  sea-based  strategic  deterrent. We must have sea control to conduct sustained U.S.  Army  and  U.S.  Air  Force  operations  abroad. Modern land warfare requires large quantities of  supplies;  most  of  them  must  be  supplied by sea. We maintain sea control by destroying or neutralizing hostile forces in maritime areas the United States must use. Hostile forces include aircraft, surface ships, and submarines that threaten  U.S.  or  friendly  forces  operating  in  those areas. The  Navy  achieves  or  supports  sea  control through the following operations: 1. Locating and destroying hostile naval combat  units 1-2