National security is the requirement to maintain the survival of the state through the use of economic power, diplomacy, power projection and political power. The concept developed mostly 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:
A police officer (also known as a policeman, police agent, patrolman, cop, policewoman, and constable in some forces, particularly in the United Kingdom and other Commonwealth nations) is a warranted employee of a police force. In the United States, "officer" is the formal name of the lowest police rank. In many other countries, "officer" is a generic term not specifying a particular rank, and the lowest rank is often "constable". In many other countries there is no such title as "police officer", as the use of the rank "officer" is legally reserved for military personnel only and thus not applicable. Police officers are generally charged with the apprehension of criminals and the prevention and detection of crime, and the maintenance of public order. Police officers may be sworn to an oath, and have the power to arrest people and detain them for a limited time, along with other duties and powers.
Some police officers may also be trained in special duties, such as counter-terrorism, surveillance, child protection, VIP protection, and investigation techniques into major crime, including fraud, rape, murder and drug trafficking.