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