KNOW ABOUT WARNING
An enemy attack on the United States probably would be preceded by a period of international tension or crisis. This crisis period would help alert all citizens to the possibility of attack.
If an attack actually occurs, it is almost certain that incoming enemy planes and missiles would be detected by our networks of warning stations in time for citizens to get into shelters or at least take cover. This warning time might be as little as 5-15 minutes in some locations, or as much as an hour or more in others.
How you received warning of an attack would depend on where you happened to be at that time. You might hear the warning given on radio or television, or even by word-of-mouth. Or your first notice of attack might come from the outdoor warning system in your own city, town or village.
Many U.S. cities and towns have outdoor warning systems, using sirens, whistles, horns or bells. Although they have been installed mainly to warn citizens of enemy attack, some local governments also use them in connection with natural disasters and other peacetime catastrophes.
Different cities and towns are using their outdoor warning systems in different ways. Most local governments, however, have decided to use a certain signal to warn people of an enemy attack, and a different signal to notify them of a peacetime disaster.