Civil defense or civil protection is an effort to protect the citizens of a state (generally non-combatants) from military attack. It uses the principles of emergency operations: prevention, mitigation, preparation, response, or emergency evacuation and recovery. Programs of this sort were initially discussed at least as early as the 1920s and were implemented in some countries during the 1930s as the threat of war and aerial bombardment grew. It became widespread after the threat of nuclear weapons was realized. Since the end of the Cold War, the focus of civil defense has largely shifted from military attack to emergencies and disasters in general. The new concept is described by a number of terms, each of which has its own specific shade of meaning, such as crisis management, emergency management, emergency preparedness, contingency planning, emergency services, and civil protection.
As the threat of Cold War eased, a number of such civil defense organisations have been disbanded or mothballed (as in the case of the Royal Observer Corps in the United Kingdom and the United States civil defense), while others have changed their focuses into providing rescue services after natural disasters (as for the State Emergency Service in Australia). However the ideals of Civil Defense [clarification needed] have been brought back in the United States under FEMA's Citizen Corps and Community Emergency Response Team (CERT).