The Homeland Security threat level, or Threat Condition, for the United States (US) is determined by the US Attorney General in conjunction with the Department of Homeland Security. While there are some guides to how it is determined, ultimately it comes down to information that US security and intelligence agencies have regarding the potential of an attack against the US. The Homeland Security threat level is based on qualitative information about the likelihood of an attack against the US, and is not based upon any sort of quantitative, or numerical, system.
Following the attacks against the US on 11 September 2001, the Department of Homeland Security established the Homeland Security Advisory System. This system indicates the Homeland Security threat level through a series of color-coded indicators. The Homeland Security threat level consists of five levels of threat advisories: green for a low level of threat, blue for a guarded or general risk of threat, yellow for an elevated level of threat, orange for a high level of threat, and red for a severe risk of threat.
Threat level at any given time is established by the US Attorney General, who consults with intelligence agencies such as the Department of Homeland Security, the Federal Bureau of Investigation, and the Central Intelligence Agency for security information regarding potential threats. The Attorney General then sets or adjusts the Homeland Security threat level based upon the information he or she has received. By showing the threat level to the public, the hope is that people will adjust their behaviors and be more vigilant in watching for potential threats and risks.
There have been criticisms, however, of the advisory system and how the Homeland Security threat level is established and explained. On numerous occasions, the threat level has been adjusted due to a “non-specific threat” or a specific threat that could not be identified publicly due to national security issues. For many critics, this lack of transparency has often been seen as reducing the effectiveness of the advisory system. Since people are not told what the threat is, critics say, the change to the Homeland Security threat level really does not help convey any useful information.
Other critics have even warned that the use of the advisory system could ultimately serve to harm the public well-being, since it also serves to alert potential attackers of when the US may be aware of some type of attack. Defenders of the advisory system, however, claim that communicating changes to the Homeland Security threat level is important even without specific details, and that alerting potential attackers can act as a deterrent. In 2009, a bipartisan task force to President Barack Obama recommended the advisory system be changed to only the three highest threat levels, as the threat level had never gone into blue or green in the eight years following the creation of the advisory system.