federal executive division conceived in the wake of the terrorist attacks of September 11, 2001, to unite domestic national security functions that had previously been spread across some 40 federal agencies into a single, Cabinet-level department. The department became operational in 2003 and its major components include the Transportation Security Administration (TSA), which is responsible for protecting the nation's transportation systems and employs 60,000 security officers, inspectors, air marshals, and staff; U.S. Customs and Border Protection (q.v.), whose functions and staff had been under the former U.S. Customs Service and the former Immigration and Naturalization Service; U.S. Citizenship and Immigration Services (q.v.), which also was a successor agency to the former Immigration and Naturalization Service; U.S. Customs and Immigration Enforcement (ICE), which enforces laws relating to border patrol, customs, trade, and immigration; Federal Emergency Management Agency (FEMA), which aims to reduce the loss of life and property and help communities protect themselves from, prepare for, and respond to natural and man-made hazards and from acts of terrorism; the U.S. Secret Service, an investigative and protective service with responsibilities ranging from currency fraud to protection of the president and other national leaders; and the U.S. Coast Guard (q.v.).