The largest federal agency in the United States is the Department of Defense (DoD). It oversees the nation's military forces and is responsible for national security, including the Army, Navy, Air Force, and Marine Corps. The DoD has the largest budget of any federal agency and employs millions of military and civilian personnel. Its extensive operations and global presence make it a critical component of the U.S. government.
department of defense
The Environmental Protection Agency.
That would be FEMA which stands for the Federal Emergency Management Agency.
Social Security Administration.
the Department of Defense
Where? In the US its the IRS.
employee (US Federal worker and/or manager)
The Federal Government
The National Security Agency.
In the US, the federal agency responsible for enforcing import and export laws is the U.S. Customs and Border Protection (CBP).
http://www.answers.com/topic/us-department-of-defense
FDA