The U.S. Diplomatic Security Service (DSS or DS) is the federal law enforcement arm of the United States Department of State. The majority of its Special Agents are members of the Foreign Service and American federal law enforcement officers at the same time, making them unique from other federal law enforcement agencies, most of which are in the civil service. Both DSS and DS, are used interchangeably inside and outside the State Department to refer to Diplomatic Security. The Diplomatic Security Service is the federal law enforcement agency, within the State Department, primarily made up of U.S. federal law enforcement agents mandated to serve overseas and domestically. DS agents can only serve 6 years in a domestic position at a time – the rest must be served overseas in 1-3 year blocks. Therefore, DS is the most widely represented U.S. law enforcement agency in the world.