Counterintelligence (CI) refers to efforts made by intelligence organizations to prevent hostile or enemy intelligence organizations from successfully gathering and collecting intelligence against them. National intelligence programs, and, by extension, the overall defenses of nations, are vulnerable to attack. It is the role of intelligence cycle security to protect the process embodied in the intelligence cycle, and that which it defends. A number of disciplines go into protecting the intelligence cycle. One of the challenges is there is a wide range of potential threats, so threat assessment, if complete, is a complex task. Many governments organize counterintelligence agencies separate and distinct from their intelligence collection services for specialized purposes. In most countries the counterintelligence mission is spread over multiple organizations, though one usually predominates. There is usually a domestic counterintelligence service, perhaps part of a larger law enforcement organization such as the FBI in the United States.