This mistake 50 years ago caused a nationwide panic that the United States was under attack
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Saturday is the 50th anniversary of a harrowing moment during the Cold War.

The event was recounted by Stephen Schwartz, a nonresident senior fellow at the Bulletin of the Atomic Scientists.

"Fifty years ago today, a teletype operator at the National Emergency Warning Center in Cheyenne Mountain, CO, mistakenly transmitted a message via the Emergency Broadcast System notifying radio and TV stations nationwide the United States was under attack," Schwartz posted in a Twitter thread, with an image of the original document.

"Wayland Eberhardt's errant message sparked major panic and confusion as stations, following protocol, went off the air that Saturday and scrambled to understand the nature of the emergency and keep their listeners and viewers informed," he explained, posting a YouTube clip of a station in Fort Wayne, Indiana.

WOWO EBS False Alarm: February 20, 1971

"Although officials notified stations it was a false alarm after about five tense minutes, it took a full 40 minutes for National Emergency Warning Center staff to locate the valid authenticator codeword ("IMPISH") and transmit a message officially terminating the mistaken alert," he added.

Here is his thread: