sphere of influence, term formerly applied to an area over which an outside power claims hegemony with the intention of subsequently gaining more definite control, as in colonization colonization, extension of political and economic control over an area by a state whose nationals have occupied the area and usually possess organizational or technological superiority over the native population.
..... Click the link for more information. , or with the intention of securing an economic monopoly over the territory without assuming political control. A sphere of influence was usually claimed by an imperialistic nation over an underdeveloped or weak state that bordered an already existing colony. The expression came into common use with the colonial expansion of European powers in Africa during the late 19th cent. A sphere of influence was formalized by treaty, either between two colonizing nations who agreed not to interfere in one another's territory, or between the colonizing nation and a representative of the territory. Theoretically, the sovereignty sovereignty, supreme authority in a political community. The concept of sovereignty has had a long history of development, and it may be said that every political theorist since Plato has dealt with the notion in some manner, although not always explicitly.
..... Click the link for more information. of a nation was not impaired by the establishment of a sphere of influence within its borders; in actuality, the interested power was able to exercise great authority in the territory it dominated, and if disorders occurred it was in a position to seize control. Thus the creation of spheres of influence was frequently the prelude to colonization or to the establishment of a protectorate protectorate, in international law, a relationship in which one state surrenders part of its sovereignty to another. The subordinate state is called a protectorate.
..... Click the link for more information. . The term in this sense is no longer recognized in international law, however. Currently, it is used by the more powerful nations of the world to denote the exclusive or predominant interest they may have in certain areas of the globe, especially for the purposes of national security.

sphere of influence

In international politics, a state's claim to exclusive or predominant control over a foreign area or territory. Beginning in the late 1880s, European colonial powers undertook legal agreements consisting of promises not to interfere with each other's actions in mutually recognized spheres of influence in Africa and Asia. After colonial expansion ceased, geopolitical rather than legal claims to spheres of influence became common, examples being the U.S. claim to dominance in the Western Hemisphere under the much-earlier Monroe Doctrine and the Soviet Union's expansion of its sphere of influence to eastern Europe following World War II. See also Iron Curtain.