When Britain Nuked America....Twice! Operation Sky Shield 🇬🇧🇬🇧🇬🇧 Operation Sky Shield, sometimes known as Exercise Skyshield, was a series of three large-scale military exercises conducted in the United States in 1960, 1961, and 1962 by the North American Aerospace Defense Command (NORAD) and the Strategic Air Command (SAC) to test defences against an air attack from the USSR. The tests were intended to ensure that any attacks over the Canada–US border or coastlines would be detected and s