Sphere of interest

In the field of international relations, a sphere of influence (SOI) is a spatial region or concept division over which a state or organization has a level of cultural, economic, military, or political exclusivity, accommodating to the interests of powers outside the borders of the state that controls it.

While there may be a formal alliance or other treaty obligations between the influenced and influencer, such formal arrangements are not necessary and the influence can often be more of an example of soft power. Similarly, a formal alliance does not necessarily mean that one country lies within another's sphere of influence. High levels of exclusivity have historically been associated with higher levels of conflict.

In more extreme cases, a country within the "sphere of influence" of another may become a subsidiary of that state and serve in effect as a satellite state or de facto colony. The system of spheres of influence by which powerful nations intervene in the affairs of others continues to the present. It is often analyzed in terms of superpowers, great powers, and/or middle powers.

An example of spheres of influence was China in the late 19th and early 20th Century, when Britain, France, Germany, and Russia (later replaced by Japan) had de facto control over large swaths of territory. These were taken by unequal treaties or as very long term "leases". These powers (and the United States) might have their own courts, post offices, commercial institutions, railroads, and gunboats in what was on paper Chinese territory. The system ended with the Second World War.

For another example, during the height of its existence in World War II, the Japanese Empire had quite a large sphere of influence. The Japanese government directly governed events in Korea, Vietnam, Taiwan, and parts of China. The "Greater East Asia Co-Prosperity Sphere" could thus be quite easily drawn on a map of the Pacific Ocean as a large "bubble" surrounding the islands of Japan and the Asian and Pacific nations it controlled.

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Wikipedia