The Homeland Security Department officially announced April 20 implementation of the new terrorism alert system to replace the discarded color-coded scheme instituted in the months after the terrorist attacks of Sept. 11, 2001.

The new system--dubbed the "National Terrorism Advisory System" and which doesn't swing into effect until April 26--is meant to be more concise and include a clear statement on the nature of the threat. Threats will be classified according to whether it is "elevated" or "imminent." Alerts could specify which geographic area and sector (such as "aviation") the threat affects. Alerts will also now automatically expire after a set period of time unless new information comes to light.

Threat alerts will also be distributed to the public via social media, including Facebook (link) and Twitter (link)--as well as via email and the web (sign up here for email alerts).

As of the morning of April 21, 2,431 people have liked the Facebook page and 4,392 people signed up to follow the Twitter feed.

For more:
- go to the National Terrorism Advisory System webpage

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