National security is the belief of a polity’s citizens that their territorial boundaries and collective economic and social interests are safe from external, internal, and environmental threats. National security reflects the perceived and physical condition of safety and territorial integrity of a polity.

Although the term is associated with the modern nation-state and post–World War II and postcolonial international power relations, the goal of safety and territorial integrity is ancient, and the measures taken to attain this goal vary. Currently, there are at least two operating approaches to national security. One approach addresses issues of power between and within nations. The other approach addresses the human factor in terms of the survival of people in changing domestic and international environmental and economic conditions.

Complexities arise as the ...