Clandestine human intelligence

Clandestine human intelligence is intelligence collected from human sources (HUMINT) using clandestine espionage methods. These sources consist of people working in a variety of roles within the intelligence community. Examples include the quintessential spy (known by professionals as an asset or agent), who collects intelligence; couriers and related personnel, who handle an intelligence organization's (ideally) secure communications; and support personnel, such as access agents, who may arrange the contact between the potential spy and the case officer who recruits them. The recruiter and supervising agent may not necessarily be the same individual. Large espionage networks may be composed of multiple levels of spies, support personnel, and supervisors. Espionage networks are typically organized as a cell system, in which each clandestine operator knows only the people in his own cell, perhaps the external case officer, and an emergency method (which may not necessarily involve another person) to contact higher levels if the case officer or cell leader is captured, but has no knowledge of people in other cells. This cellular organization is a form of compartmentalisation, which is an important tactic for controlling access to information, used in order to diminish the risk of discovery of the network or the release of sensitive information.

Black's Law Dictionary (1990) defines espionage as: "gathering, transmitting, or losing ... information related to the national defense."

In the UK, "Under the 1911 Act, a person commits the offence of 'spying' if he, for any purpose prejudicial to the safety or interests of the State;

The US defines espionage towards itself as "The act of obtaining, delivering, transmitting, communicating, or receiving information about the national defense with an intent, or reason to believe, that the information may be used to the injury of the United States or to the advantage of any foreign nation. Espionage is a violation of 18 United States Code 792–798 and Article 106, Uniform Code of Military Justice."

See List of intelligence agencies for a more complete list

Espionage is usually part of an institutional effort (i.e., governmental or corporate espionage), and the term is most readily associated with state spying on potential or actual enemies, primarily for military purposes, but this has been extended to spying involving corporations, known specifically as industrial espionage. Many nations routinely spy on both their enemies and allies, although they maintain a policy of not making comment on this. In addition to utilizing agencies within a government many also employ private companies to collect information on their behalf such as SCG International Risk and others.

Not all clandestine human sources change their loyalties to the country to which they were born, or owed their first allegiance. In this section we are talking of the classical and actually rare "spy", who really is a loyal citizen of country A but obtains information from country B, either through informal means (e.g., fake news reporting) or actually going to work for country B.

A special case is of the Country B loyalist who controls agents or provides other supporting or managerial functions against Country A.