Spy and secret agent redirect here; for alternate use, see Spy (disambiguation) and Secret agent (disambiguation).

Espionage is the practice of obtaining secrets (spying) from rivals or enemies for military, political, or economic advantage. It is usually thought of as part of an organized effort (i.e., governmental or corporate). A spy is an agent employed to obtain such secrets. The definition has been restricted to a 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 their enemies, and allies, although they generally deny this. Black's Law Dictionary (1990) defines espionage as: "...gathering, transmitting, or losing...[information related to the national defense]."

Incidents of espionage are well documented throughout history. The wisdom of Sun-Tzu contains information on deception and subversion. The ancient Egyptians had a thoroughly developed system for the acquisition of intelligence. And more recently, in Elizabethan times, there was a deeply entrenched network of intelligence gathering (run by Sir Francis Walsingham).

Espionage, by a citizen of the target state, is generally considered to be a form of treason. In many countries espionage is a crime punishable by death or life imprisonment. For example, espionage is still a capital crime in the USA; however, the death penalty is rarely used in espionage cases in the U.S. since the government will bargain away a death penalty sentence in exchange for information.

In Britain a foreign spy would face up to 14 years imprisonment under the Official Secrets Act while a Briton who spied for a foreign country would face a maximum life sentence for treason if it could be proved they were aiding Britain's enemies. Spying for proscribed terrorist organisations violates the Terrorism Act 2000. During the Second World War German spies in Britain were executed for treachery, a special offense covering any aid given to the enemy, including by foreign nationals.

The Cold War involved intense espionage activity between the United States of America and its allies and the Soviet Union and the People's Republic of China and their allies, particularly related to nuclear weapons secrets.

Recently, espionage agencies have targeted the illegal drug trade and those considered to be terrorists. Spies have also engaged in assassination and kidnap of people who are considered threats to their country, for example the Israeli intelligence agency Mossad. Intelligence agencies have also been involved in covert and overt paramilitary activity (including assassination, kidnap, sabotage, guerrilla warfare, more conventional warfare behind enemy lines and coups d'état), this included many CIA operations during the Cold War and the current "war on terrorism".

See: Cold War espionage

Noteworthy Incidents in the History of Espionage

• Attempted Assassination of Fidel Castro by CIA
• U-2 Crisis of 1960
• Capture of Adolf Eichmann by Mossad in 1960
• USS Pueblo capture by North Korea
• USS Liberty incident (US spy ship attacked by Israel in 1967)
• Gulf of Tonkin Incident
• VENONA Project (break of Soviet spy codes by US and UK)
• Chinese theft of American nuclear secrets over the course of several decades--and likely continuing to the present day--as documented in the Cox report

Spies in various conflicts

• American Civil War spies

Espionage organizations

• Australia: DSD, ASIO, ASIS, ONA, DIO
• Canada: CSIS, CSE
• India: RAW, IB, JIC, DIA
• Israel: Mossad
• South Africa: BOSS (in the days of apartheid)
• Soviet Union: KGB (several previous/subsequent names), GRU
• UK: MI5, MI6, GCHQ, Special Branch
• USA: CIA, DIA, NSA, NRO

See also Intelligence agencies and Special Operations Executive

Intelligence disciplines

See List of intelligence gathering disciplines

• SIGINT — Intelligence gathered by intercepting communications.
• HUMINT — Intelligence gathered by a person on the ground.
• ELINT — Intelligence gathered from electronic sensors.
• OSINT — Intelligence gathered from open sources.
• IMINT — Intelligence gathered via satellite and aerial photography.
• MASINT — A catch-all term that refers to intelligence gathering activities that bring together disparate elements that do not fit within the definitions of SIGINT, IMINT, or HUMINT.

Espionage technology and techniques

• ECHELON
• Cryptography
• Steganography
• Dead drop
• Cut-out
• Eavesdropping
• Surveillance
• One Time Pad
• One Way Voice Link
• Concealment Devices
• Agent Handling
• Interrogation
• Black Bag Operations
• False Flags
• Honey trap
• TEMPEST — Protection devices for communication equipment.

Spy fiction

Main article: Spy fiction

Since not much is publicly known about real-life secret agents, the popular conception of the secret agent has been formed largely by 20th and 21st century literature and cinema. Similar to the character of the private eye, the secret agent is usually a loner, sometimes amoral, an existential hero operating outside the everyday constraints of society. James Bond, the protagonist of Ian Fleming's novels who went on to spawn an extremely successful film franchise, is probably the most famous fictional secret agent of all.