The White House hopes the system will give law enforcement agencies and the public a clearer sense of the risk of attack.
According to Ridge, federal agencies will put the system into effect immediately, while state and local governments will be asked to voluntarily implement the plan over the next few months.
The homeland security director detailed the plan before an audience of law enforcement officers and public officials.
“The American people want to know what is behind these alerts, and perhaps more importantly, what we shall do in reponse to them,” Ridge said.
Attorney General John Ashcroft will set the alert level, after consulting with Ridge and President Bush.
The most serious of the five-level system is red, which indicates a severe risk and would result in deployment of armed forces and possible grounding of air travel.
The second level of alert is orange, indicating “high risk.” Under this alert, the federal government would be prompted to reinforce local law enforcement agencies with federal troops, and even order some federal workers to stay home.
The next step down is yellow, indicating a “significant” or “elevated’ risk of attack. Law enforcement agencies would increase surveillence at key sites and implement contingency plans.
The U.S. is currently on yellow alert, and will remain so for the “foreseeable future,” according to Ridge.
A blue level of threat indicates a “general risk,” where federal agencies would test their emergency communications equipment.
And finally, under a green alert, there is a “low risk of terrorist attacks.”
“I think it’s a substantial improvement over how we previously operated,” Ridge said in an interview this morning.
Ridge added that federal, state, local governments had reached a consensus in deciding how to better inform the public.
“The heart of what we’re doing is to maximize public safety and maximize public awareness,” Ridge said. Since the assessments are based on information received by the CIA, FBI and other agencies, Ridge warned the alerts are not foolproof. “There’s a little science in here and a lot of art.”
Since September 11, the FBI has issued four terrorist warnings.
The color-coded system was designed after critics called government warnings since Sept. 11 too vague to be helpful to police and the public.