By the 1930s it was clear for some politicians and diplomats that the League of Nations had failed to become an international forum. To many it was tied to the post World War I revanchist settlement of Europe. Several nations in order to keep their colonial or territorial gains or political and economical hegemony formed regional blocs.

Its background and initial conceptualization can be traced to the Americas. US isolation after World War I, Monroe Doctrine, and Pan-American suspicious of unchecked US intervention. Some countries feeling threatened created the South Alliance (1920) and later institutionalized the Pan-American Union (1924) along the US. It became in short time a relatively closed space in terms economic, political and military activity. This was helped in part by geographical barriers with the rest of the world, a large industrial nation (USA) that had the need of markets, and open cooperation.

After the Russian revolution a similar entity would be created - International Community of Socialist States (ICSS, 1935), but has a mean to defend itself against the perceived "aggression" and initial boycott of capitalist nations. By the mid 1930s the main colonial empires (France, United Kingdom and Netherlands) established their own regional structures.

Regional blocs can be defined has either intergovernmental organizations or supranational unions. Regional blocs usually form a closed economic space or union, a monetary union (or pegged currencies), have a joint or common military structure and share a common foreign affairs policy. Some because of their industrial and trade development and military power they control within their territories, have become key arbiters of international affairs. The first tier, consists of regional blocs that have this capacity.

Some countries like the Confederation of Arab States (CAS) and China, although they are not regional organizations, by means of the control of energy resources, like oil and gas (CAS) or large population, or high agricultural and industrial production (China, before joining the East Asian Community) have a similar characteristics of a regional bloc.

Some authors, mainly within the ICSS, have described this arrangement of world affairs has a new imperialism.

Cooperation does exist, specially after the Great Pacific War, between US (Pan-American Union) and FSR (ICSS) in maintaining the present status quo.

Established and historical regional blocs

The first tier regional blocs, that have the status of world powers, are:

The second tier regional blocs are:

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