The term sea power covers the control of international trade and commerce, the operation of navies in war, and the use of navies as instruments of diplomacy, deterrence, and political influence in peacetime. The importance of a navy rests on its ability to affect events on land and to control use of the sea. Armies control territory, whereas navies control access; to territory, international movement, and trade.
Unlike the concept of land and air power which are generally defined only in military terms sea power can never quite be separated from its geo-economic purposes. Over 90 percent of international trade by weight and volume travels by water. The majority of the world’s major cities and urban population lie within 200 kilometres of a coastline.
Sea power is seen as essential to globalization. A global navy alows a nation commited to global trade to guarantee the free use of trade routes. If international trade is secure from threats to its disruption, trade can expand.
Sea control and sea denial involve struggles over the use of sea lines of communication (or commerce). These are the world’s trade routes and routes for military movement at sea. The world’s geography affords three strategic choke points: The Strait of Hormuz at the mouth of the Arabian Gulf through which much of the world’s oil supply passes; the Straits of Malacca in south-east Asia, and the Panama Canal.
The only global sea power today is the United States of America. All other sea-faring nations concentrate on being local or regional sea powers, controlling their littoral region and maintaing a small expeditionary force which can be sent to areas of strategic interest when needed.