A nation's security is its ultimate foreign policy priority. Because the powerful – and sometimes the powerless – often regard coercion as the most direct way of achieving their objectives, the possibility of being threatened with or subjected to force is a persistent attribute of relations among societies. In his 1651 masterpiece, Leviathan, the English philosopher Thomas Hobbes argued that the drive for security underlies all politics, because humans living in a persistent state of fear and insecurity are unable to fulfil any of the higher purposes of human existence:

For any state, then, its security against coercion is an existential value: without security it cannot maintain any independence or work with confidence towards the values held to be important by its own society.