U.S. Customs and Border Protection (CBP) is the largest federal law enforcement agency of the United States Department of Homeland Security. It is charged with regulating and facilitating international trade, collecting import duties, and enforcing U.S. regulations, including trade, customs, and immigration. CBP is the largest law enforcement agency in the United States. It has a workforce of more than 45,600 sworn federal agents and officers. It has its headquarters in Washington, D.C.