During the 1950s, a nationwide network of air raid warning sirens was produced for Canada. These sirens were manufactured by CLM Industries in order to warn urban populations of a possible nuclear attack from the Soviet Union. The siren system was tested twice nationally in 1961, under the code names "Exercise Tocsin" and "Tocsin B." The network was maintained until the 1970s, when advancements in military technology reduced the Soviet nuclear missile strike time to less than 15 minutes, thus rendering the sirens unnecessary. The federal government proceeded to remove them throughout the country, but some were missed. These government-abandoned sirens can still be found today, in various states of repair. 1