Homeland Security Secretary Janet Napolitano said the National Terrorism Advisory System is replacing the color-coded system effective next Tuesday.
Napolitano said the new alert system was developed in collaboration with federal, state and local officials to provide the U.S. public with the most credible information on potential terrorist threats.
"The terrorist threat facing our country has evolved significantly over the past 10 years and, in today's environment more than ever, we know that the best security strategy is one that counts on the American public as a key partner in securing our country," she said in a statement.
The alert system spells out an "elevated threat" level that warns of a credible threat, and an "imminent threat," which warns of a specific and impending threat against the United States.
The Homeland Security Department in March 2002 adopted a five-tier, color-coded alert system to represent the threat of a terrorist attack. The color-coded system ranged from green, meaning a low risk of terrorist attack, to red, indicating an imminent threat.
The Homeland Security Web site Wednesday posted the color-coded advisory, putting the setting at "yellow," its signal of a "significant risk of terrorist attacks."