The United States Department of Homeland Security ( DHS ) , commonly known in the United States as `` Homeland Security '' , is a Cabinet department of the U.S. federal government with the duty of protecting the U.S. from terrorist attacks and helping when there is a natural disasters . The United States Department of Homeland Security ( DHS ) is a cabinet department of the United States federal government , created in response to the September 11 attacks , and with the primary responsibilities of protecting the territory of the U.S. from terrorist attacks and responding to natural disasters .