The term “‘sphere of influence’ … entered the vocabulary of diplomacy in the early 19th century,” according to Harvard’s Graham Allison, “but the concept is as old as international relations itself.” By way of illustration, Allison invokes the image of a “shadow” cast by a state that has become predominant after “the equilibrium of forces” between it and another state has shifted greatly enough. “Traditionally,” he goes on, “great powers have demanded a degree of deference from lesser powers on their borders and in adjacent seas, and they have expected other great powers to respect that fact.” While this definition does not seem to be contested by experts, the right of countries to claim spheres of influence certainly is.
