Rivalry is endemic to the nation-state system. The logic of the nation-state system breeds insecurity, distrust, rivalry, and hostility. In theory all members are enemy to the others, but in practice the international system at any given time does not generally comprise all nations attracting and repelling each other at random. Or two rivals may seek to make an alliance with the state on the opponent's other border. Another pattern was illustrated when Great Britain, confronted by the emergence of Wilhelmian Germany as both a naval rival and as a threat to European balance of power after 1890, relinquished its ambitions in the Caribbean in favor of the United States and in the area of Manchuria in favor of Japan.
Rivalry is also endemic to the nation-state system for psychological reasons.
Citizens and nations seek to establish their identity, a process that often manifests itself in hostility toward others. This anxiety and hostility is always seeking an object. This reaction invariably reinforces the relationship of hostility and rivalry born of the security dilemma. This process may build up to a military eruption or it may subside, but patterns of conflict and hostility are an enduring aspect of relations between nation-states. The postwar relationship of the United States and the soviet Union was conducive to just such an outcome.