National Terrorism Advisory System
The National Terrorism Advisory System (NTAS) is a terrorism threat advisory scale used by the United States Department of Homeland Security (DHS) since April 26, 2011. The NTAS is the replacement for the often-criticized, color-coded Homeland Security Advisory System introduced by the George W. Bush administration in 2002.
Source: Wikipedia — National Terrorism Advisory System (CC BY-SA 4.0)