United States Department of Homeland Security

The United States Department of Homeland Security is the U.S. federal executive department responsible for public security, roughly comparable to the interior or home ministries of other countries. Its stated missions involve anti-terrorism, border security, immigration and customs, cyber security, and disaster prevention and management.
It began operations in 2003, formed as a result of the Homeland Security Act, enacted the previous year in response to the 9/11 attacks. With more than 240,000 employees, DHS is the third largest Cabinet department, after the Departments of Defense and Veterans Affairs. Homeland security policy is coordinated at the White House by the Homeland Security Council. Other agencies with significant homeland security responsibilities include the Departments of Health and Human Services, Justice, and Energy.

Wikipedia