The United States Department of Homeland Security (DHS), commonly known in the United States as Homeland Security, is a Cabinet department of the Federal Government of the United States with the responsibility of protecting the territory of the United States from terrorist attacks and responding to natural disasters.
Whereas the Department of Defense is charged with military actions abroad, the Department of Homeland Security works in the civilian sphere to protect the United States within, at, and outside its borders. Its goal is to prepare for, prevent, and respond to domestic emergencies, particularly terrorism. On March 1, 2003, the DHS absorbed the now defunct United States Immigration and Naturalization Service (INS), and assumed its duties.
With over 200,000 employees, DHS is the third largest cabinet department in the U.S. federal government after the Department of Defense and Department of Veterans Affairs. Homeland security policy is coordinated at the White House by the Homeland Security Council, with Frances Townsend as the Homeland Security Advisor. Other agencies with significant homeland security responsibilities include the Department of Health and Human Services, the Department of Justice, and the Department of Energy.
On March 12, 2002, the Homeland Security Advisory System (HSAS), a color-coded terrorism risk advisory scale, was created as a Presidential Directive to provide a "comprehensive and effective means to disseminate information regarding the risk of terrorist acts to Federal, State, and local authorities and to the American people."- Many procedures at government facilities are keyed off of the alert level; for example a facility may search all entering vehicles when the alert is above a certain level. Since January 2003, it has been administered in coordination with the DHS; it has also been the target of frequent jokes and ridicule on the part of the administration's detractors about its ineffectiveness. After resigning, Tom Ridge stated that he didn't always agree with the threat level adjustments pushed by other government agencies.
In January 2003, the office was merged into the Department of Homeland Security and the White House Homeland Security Council, both of which were created by the Homeland Security Act of 2002. The Homeland Security Council, similar in nature to the National Security Council, retains a policy coordination and advisory role and is led by the Assistant to the President for Homeland Security.