The concept of regional security complexes covers how security is clustered in geographically shaped regions. Security concerns do not travel well over distances and threats are therefore most likely to occur in the region. The security of each actor in a region interacts with the security of the other actors. There is often intense security interdependence within a region, but not between regions, which is what defines a region and what makes regional security an interesting area of study. Insulator states sometimes isolate regions; an example is
Afghanistan's location between the
Middle East and
South Asia. Insulators mark boundaries of indifference, where security dynamics stand back to back. They contrast with the traditional idea of "
buffer states" which are located at points where security dynamics are intense (e.g. Belgium between Germany and France). Regions should be regarded as mini-systems in which all other international relations (IR) theories can be applied, such as
balance of power theory, polarity, interdependence, alliance systems, etc.
Regional security complex theory should not be confused with
regionalism, a subset of IR from the 1970s concerned mostly with regional integration. == Securitization ==