By Laura DeKoven Waxman
April 25, 2011

Homeland Security Secretary Janet Napolitano announced at an April 20 press conference in New York City's Grand Central Terminal the implementation of a new National Terrorism Advisory System (NTAS). Accompanying her at the announcement were New York City Police Commissioner Raymond Kelly and New York Representatives Peter King, Chair of the House Homeland Security Committee, and Carolyn Maloney. The new system replaces the color-coded alert system instituted following the attacks of September 11, 2001.

The new system includes two categories of threats:

• An "Elevated Threat" warns of a credible terrorist threat against the United States.

• An "Imminent Threat" warns of a credible, specific, and impending terrorist threat against the United States.

DHS materials state that "NTAS alerts provide a concise summary of the potential threat including geographic region, mode of transportation, or critical infrastructure potentially affected by the threat, actions being taken to ensure public safety, as well as recommended steps that individuals, communities, business and governments can take to help prevent, mitigate or respond to a threat."

DHS further explains that alerts will be issued for a specific time period and will expire automatically, and that they may be extended if new information becomes available or as a specific threat evolves. Depending on the nature of the threat, alerts may be sent to law enforcement, distributed to affected areas of the private sector, or issued more broadly to the public through both official and social media channels.

A public guide and other information on the new system are available at http://www.dhs.gov/files/programs/ntas.shtm.