National security is a concept that a government, along with its parliaments, should protect the state and its citizens against all kind of "national" crises through a variety of power projections, such as political power, diplomacy, economic power, military might, and so on.
The concept developed all in the United States after World War II. Initially focusing on military might, it now encompasses a broad range of facets, all of which impinge on the non-military or economic security of the nation and the values espoused by the national society. Accordingly, in order to possess national security, a nation needs to possess economic security, energy security, environmental security, etc. Security threats involve not only conventional foes such as other nation-states but also non-state actors such as violent non-state actors, narcotic cartels, multinational corporations and non-governmental organisations; some authorities include natural disasters and events causing severe environmental damage in this category.
Measures taken to ensure national security include:
There is no single universally accepted definition of national security. The variety of definitions provide an overview of the many usages of this concept. The concept still remains ambiguous, having originated from simpler definitions which initially emphasised the freedom from military threat and political coercion to later increase in sophistication and include other forms of non-military security as suited the circumstances of the time.