The United States Department of Homeland Security (DHS) is a U.S. federal executive department, created in 2002 in response to the September 11, 2001, terrorist attacks, responsible for domestic/public security and disaster response. Modeled roughly on interior, home, or public security ministries in other countries, it consolidated 22 previously independent federal agencies into a single cabinet-level department to enhance coordination and efficiency in homeland security efforts.

DHS’s missions encompass national security and counterterrorism; border protection, immigration enforcement, customs and facilitation of lawful trade and travel; transportation and maritime security (including sea rescue); civil defense and disaster response and recovery; cybersecurity for critical infrastructure and defenses against cyber attacks; and the prevention and mitigation of weapons of mass destruction. To carry out these responsibilities, the department operates through multiple components, including U.S. Customs and Border Protection (CBP), U.S. Immigration and Customs Enforcement (ICE), U.S. Citizenship and Immigration Services (USCIS), the Federal Emergency Management Agency (FEMA), and the Transportation Security Administration (TSA), among others.

DHS plays a central role in safeguarding U.S. borders, facilitating lawful immigration and trade, responding to emergencies, and sharing intelligence to maintain national security. It implements policies aimed at securing the homeland while promoting economic vitality and public safety, and continues to evolve to address modern threats such as cybersecurity challenges and mass migration.