Counterintelligence
In theory, the USA has a similar division between foreign activities and homeland activities. The Federal Bureau of Investigation (FBI) is a domestic security service. The CIA has no law enforcement function and does overseas intelligence gathering, with only limited domestic intelligence collection. In practice, the set-up is much more complex, and ever-changing. For one thing, the career of James Angleton and also the Watergate scandal shows how the CIA has been involved in mainland USA. The addition of the United States Department of Homeland Security was a recognition that the United States was itself a potential target of attack by its various enemies.