The missions of the Department of Homeland Security are to prevent and disrupt terrorist attacks; protect the American people, our critical infrastructure, and key resources; and respond to and recover from incidents that do occur. 

The third largest Cabinet department, DHS was established by the Homeland Security Act of 2002, largely in response to the terrorist attacks on September 11, 2001. The new department consolidated 22 executive branch agencies, including the U.S. Customs Service, the U.S. Coast Guard, the U.S. Secret Service, the Transportation Security Administration, and the Federal Emergency Management Agency.

DHS employs 216,000 people in its mission to patrol borders, protect travelers and our transportation infrastructure, enforce immigration laws, and respond to disasters and emergencies. 

The agency also promotes preparedness and emergency prevention among citizens. Policy is coordinated by the Homeland Security Council at the White House, in cooperation with other defense and intelligence agencies, and led by the Assistant to the President for Homeland Security.