The examples and perspective in this article deal primarily with the United States and do not represent a worldwide view of the subject. (February 2019) (Learn how and when to remove this template message)
Espionage or spying is the act of obtaining secret or confidential information or divulging of the same without the permission of the holder of the information. Spies help agencies uncover secret information. Any individual or spy ring (a cooperating group of spies), in the service of a government, company or independent operation, can commit espionage. The practice is clandestine, as it is by definition unwelcome. In some circumstances it may be a legal tool of law enforcement and in others it may be illegal and punishable by law. Espionage is a method of gathering which includes information gathering from non-disclosed sources.
Espionage is often part of an institutional effort by a government or commercial concern. However, the term tends to be associated with state spying on potential or actual enemies for military purposes. Spying involving corporations is known as industrial espionage.
One of the most effective ways to gather data and information about a targeted organization is by infiltrating its ranks. This is the job of the spy (espionage agent). Spies can then return information such as the size and strength of enemy forces. They can also find dissidents within the organization and influence them to provide further information or to defect. In times of crisis, spies steal technology and sabotage the enemy in various ways. Counterintelligence is the practice of thwarting enemy espionage and intelligence-gathering. Almost all nations have strict laws concerning espionage and the penalty for being caught is often severe. However, the benefits gained through espionage are often so great that most governments and many large corporations make use of it.
Today, espionage agencies target the illegal drug trade and terrorists as well as state actors. Between 2008 and 2011, the United States charged at least 57 defendants for attempting to spy for China.
Intelligence services value certain intelligence collection techniques over others. The former Soviet Union, for example, preferred human sources over research in open sources, while the United States has tended to emphasize technological methods such as SIGINT and IMINT. In the Soviet Union, both political (KGB) and military intelligence (GRU) officers were judged by the number of agents they recruited.
Targets of espionage
Espionage agents are usually trained experts in a targeted field so they can differentiate mundane information from targets of value to their own organizational development. Correct identification of the target at its execution is the sole purpose of the espionage operation.
Broad areas of espionage targeting expertise include:
- Natural resources: strategic production identification and assessment (food, energy, materials). Agents are usually found among bureaucrats who administer these resources in their own countries
- Popular sentiment towards domestic and foreign policies (popular, middle class, elites). Agents often recruited from field journalistic crews, exchange postgraduate students and sociology researchers
- Strategic economic strengths (production, research, manufacture, infrastructure). Agents recruited from science and technology academia, commercial enterprises, and more rarely from among military technologists
- Military capability intelligence (offensive, defensive, manoeuvre, naval, air, space). Agents are trained by military espionage education facilities and posted to an area of operation with covert identities to minimize prosecution
- Counterintelligence operations targeting opponents' intelligence services themselves, such as breaching the confidentiality of communications, and recruiting defectors or moles
Methods and terminology
Although the news media may speak of "spy satellites" and the like, espionage is not a synonym for all intelligence-gathering disciplines. It is a specific form of human source intelligence (HUMINT). Codebreaking (cryptanalysis or COMINT), aircraft or satellite photography, (IMINT) and research in open publications (OSINT) are all intelligence gathering disciplines, but none of them is considered espionage. Many HUMINT activities, such as prisoner interrogation, reports from military reconnaissance patrols and from diplomats, etc., are not considered espionage. Espionage is the disclosure of sensitive information (classified) to people who are not cleared for that information or access to that sensitive information.
Unlike other forms of intelligence collection disciplines, espionage usually involves accessing the place where the desired information is stored or accessing the people who know the information and will divulge it through some kind of subterfuge. There are exceptions to physical meetings, such as the Oslo Report, or the insistence of Robert Hanssen in never meeting the people who bought his information.
The US defines espionage towards itself as "The act of obtaining, delivering, transmitting, communicating, or receiving information about the national defence 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". Black's Law Dictionary (1990) defines espionage as: "... gathering, transmitting, or losing ... information related to the national defense". Espionage is a violation of United States law, 18 U.S.C. §§ 792–798 and Article 106a of the Uniform Code of Military Justice". The United States, like most nations, conducts espionage against other nations, under the control of the National Clandestine Service. Britain's espionage activities are controlled by the Secret Intelligence Service.
Technology and techniques
- Agent handling
- Concealment device
- Covert agent
- Covert listening device
- Cyber spying
- Dead drop
- False flag operations
- Non-official cover
- Numbers messaging
- Official cover
- One-way voice link
- Safe house
- Side channel attack
- Surveillance aircraft
A spy is a person employed to seek out top secret information from a source. Within the United States Intelligence Community, "asset" is more common usage. A case officer or Special Agent, who may have diplomatic status (i.e., official cover or non-official cover), supports and directs the human collector. Cutouts are couriers who do not know the agent or case officer but transfer messages. A safe house is a refuge for spies. Spies often seek to obtain secret information from another source.
In larger networks, the organization can be complex with many methods to avoid detection, including clandestine cell systems. Often the players have never met. Case officers are stationed in foreign countries to recruit and to supervise intelligence agents, who in turn spy on targets in their countries where they are assigned. A spy need not be a citizen of the target country—hence does not automatically commit treason when operating within it. While the more common practice is to recruit a person already trusted with access to sensitive information, sometimes a person with a well-prepared synthetic identity (cover background), called a legend in tradecraft, may attempt to infiltrate a target organization.
These agents can be moles (who are recruited before they get access to secrets), defectors (who are recruited after they get access to secrets and leave their country) or defectors in place (who get access but do not leave).
A legend is also employed for an individual who is not an illegal agent, but is an ordinary citizen who is "relocated", for example, a "protected witness". Nevertheless, such a non-agent very likely will also have a case officer who will act as a controller. As in most, if not all synthetic identity schemes, for whatever purpose (illegal or legal), the assistance of a controller is required.
Spies may also be used to spread disinformation in the organization in which they are planted, such as giving false reports about their country's military movements, or about a competing company's ability to bring a product to market. Spies may be given other roles that also require infiltration, such as sabotage.
Many governments spy on their allies as well as their enemies, although they typically maintain a policy of not commenting on this. Governments also employ private companies to collect information on their behalf such as SCG International Risk, International Intelligence Limited and others.
Many organizations, both national and non-national, conduct espionage operations. It should not be assumed that espionage is always directed at the most secret operations of a target country. National and terrorist organizations and other groups are also targeted. This is because governments want to retrieve information that they can use to be proactive in protecting their nation from potential terrorist attacks.
Communications both are necessary to espionage and clandestine operations, and also a great vulnerability when the adversary has sophisticated SIGINT detection and interception capability. Agents must also transfer money securely.
Agents in espionage
In espionage jargon, an "agent" is the person who does the spying; a citizen of one country who is recruited by a second country to spy on or work against his own country or a third country. In popular usage, this term is often erroneously applied to a member of an intelligence service who recruits and handles agents; in espionage, such a person is referred to as an intelligence officer, intelligence operative or case officer. There are several types of agent in use today:
- Double agent: "engages in clandestine activity for two intelligence or security services (or more in joint operations), who provides information about one or about each to the other, and who wittingly withholds significant information from one on the instructions of the other or is unwittingly manipulated by one so that significant facts are withheld from the adversary. Peddlers, fabricators and others who work for themselves rather than a service are not double agents because they are not agents. The fact that double agents have an agent relationship with both sides distinguishes them from penetrations, who normally are placed with the target service in a staff or officer capacity."
- Redoubled agent: forced to mislead the foreign intelligence service after being caught as a double agent.
- Unwitting double agent: offers or is forced to recruit as a double or redoubled agent and in the process is recruited by either a third-party intelligence service or his own government without the knowledge of the intended target intelligence service or the agent. This can be useful in capturing important information from an agent that is attempting to seek allegiance with another country. The double agent usually has knowledge of both intelligence services and can identify operational techniques of both, thus making third-party recruitment difficult or impossible. The knowledge of operational techniques can also affect the relationship between the operations officer (or case officer) and the agent if the case is transferred by an operational targeting officer to a new operations officer, leaving the new officer vulnerable to attack. This type of transfer may occur when an officer has completed his term of service or when his cover is blown.
- Triple agent: works for three intelligence services.
- Intelligence agent: provides access to sensitive information through the use of special privileges. If used in corporate intelligence gathering, this may include gathering information of a corporate business venture or stock portfolio. In economic intelligence, "Economic Analysts may use their specialized skills to analyze and interpret economic trends and developments, assess and track foreign financial activities, and develop new econometric and modelling methodologies." This may also include information of trade or tariff.
- Access agent: provides access to other potential agents by providing profiling information that can help lead to recruitment into an intelligence service.
- Agent of influence: provides political influence in an area of interest, possibly including publications needed to further an intelligence service agenda. The use of the media to print a story to mislead a foreign service into action, exposing their operations while under surveillance.
- Agent provocateur: instigates trouble or provides information to gather as many people as possible into one location for an arrest.
- Facilities agent: provides access to buildings, such as garages or offices used for staging operations, resupply, etc.
- Principal agent: functions as a handler for an established network of agents, usually considered "blue chip."
- Confusion agent: provides misleading information to an enemy intelligence service or attempts to discredit the operations of the target in an operation.
- Sleeper agent: recruited to wake up and perform a specific set of tasks or functions while living undercover in an area of interest. This type of agent is not the same as a deep cover operative, who continually contacts a case officer to file intelligence reports. A sleeper agent is not in contact with anyone until activated.
- Illegal agent: lives in another country under false credentials and does not report to a local station. A nonofficial cover operative can be dubbed an "illegal" when working in another country without diplomatic protection.
Espionage is a crime under the legal code of many nations. In the United States, it is covered by the Espionage Act of 1917. The risks of espionage vary. A spy violating the host country's laws may be deported, imprisoned, or even executed. A spy violating its own country's laws can be imprisoned for espionage or/and treason (which in the United States and some other jurisdictions can only occur if they take up arms or aids the enemy against their own country during wartime), or even executed, as the Rosenbergs were. For example, when Aldrich Ames handed a stack of dossiers of U.S. Central Intelligence Agency (CIA) agents in the Eastern Bloc to his KGB-officer "handler", the KGB "rolled up" several networks, and at least ten people were secretly shot. When Ames was arrested by the U.S. Federal Bureau of Investigation (FBI), he faced life in prison; his contact, who had diplomatic immunity, was declared persona non grata and taken to the airport. Ames' wife was threatened with life imprisonment if her husband did not cooperate; he did, and she was given a five-year sentence. Hugh Francis Redmond, a CIA officer in China, spent nineteen years in a Chinese prison for espionage—and died there—as he was operating without diplomatic cover and immunity.
The United States in World War I passed the Espionage Act of 1917. Over the years, many spies, such as the Soble spy ring, Robert Lee Johnson, the Rosenberg ring, Aldrich Hazen Ames, Robert Philip Hanssen, Jonathan Pollard, John Anthony Walker, James Hall III, and others have been prosecuted under this law.
History of espionage laws
From ancient times, the penalty for espionage in many countries was execution. This was true right up until the era of World War II; for example, Josef Jakobs was a Nazi spy who parachuted into Great Britain in 1941 and was executed for espionage.
In modern times, many people convicted of espionage have been given penal sentences rather than execution. For example, Aldrich Hazen Ames is an American CIA analyst, turned KGB mole, who was convicted of espionage in 1994; he is serving a life sentence without the possibility of parole in the high-security Allenwood U.S. Penitentiary. Ames was formerly a 31-year CIA counterintelligence officer and analyst who committed espionage against his country by spying for the Soviet Union and Russia. So far as it is known, Ames compromised the second-largest number of CIA agents, second only to Robert Hanssen, who is also serving a prison sentence.
Use against non-spies
Espionage laws are also used to prosecute non-spies. In the United States, the Espionage Act of 1917 was used against socialist politician Eugene V. Debs (at that time the Act had much stricter guidelines and amongst other things banned speech against military recruiting). The law was later used to suppress publication of periodicals, for example of Father Coughlin in World War II. In the early 21st century, the act was used to prosecute whistleblowers such as Thomas Andrews Drake, John Kiriakou, and Edward Snowden, as well as officials who communicated with journalists for innocuous reasons, such as Stephen Jin-Woo Kim.
As of 2012[update], India and Pakistan were holding several hundred prisoners of each other's country for minor violations like trespass or visa overstay, often with accusations of espionage attached. Some of these include cases where Pakistan and India both deny citizenship to these people, leaving them stateless. The BBC reported in 2012 on one such case, that of Mohammed Idrees, who was held under Indian police control for approximately 13 years for overstaying his 15-day visa by 2–3 days after seeing his ill parents in 1999. Much of the 13 years were spent in prison waiting for a hearing, and more time was spent homeless or living with generous families. The Indian People's Union for Civil Liberties and Human Rights Law Network both decried his treatment. The BBC attributed some of the problems to tensions caused by the Kashmir conflict.
Espionage laws in the UK
Espionage is illegal in the UK under the Official Secrets Acts of 1911 and 1920. The UK law under this legislation considers espionage as "concerning those who intend to help an enemy and deliberately harm the security of the nation". According to MI5, a person commits the offence of 'spying' if they, "for any purpose prejudicial to the safety or interests of the State": approaches, enters or inspects a prohibited area; makes documents such as plans that are intended, calculated, or could directly or indirectly be of use to an enemy; or "obtains, collects, records, or publishes, or communicates to any other person any secret official code word, or password, or any sketch, plan, model, article, or note, or other document which is calculated to be or might be or is intended to be directly or indirectly useful to an enemy". The illegality of espionage also includes any action which may be considered 'preparatory to' spying, or encouraging or aiding another to spy.
Anyone found guilty of espionage is liable to imprisonment for a term of up to 14 years in the UK, although multiple sentences can be issued.
Government intelligence laws and its distinction from espionage
Government intelligence is very much distinct from espionage, and is not illegal in the UK, providing that the organisations of individuals are registered, often with the ICO, and are acting within the restrictions of the Regulation of Investigatory Powers Act (RIPA). 'Intelligence' is considered legally as "information of all sorts gathered by a government or organisation to guide its decisions. It includes information that may be both public and private, obtained from much different public or secret sources. It could consist entirely of information from either publicly available or secret sources, or be a combination of the two."
However, espionage and intelligence can be linked. According to the MI5 website, "foreign intelligence officers acting in the UK under diplomatic cover may enjoy immunity from prosecution. Such persons can only be tried for spying (or, indeed, any criminal offence) if diplomatic immunity is waived beforehand. Those officers operating without diplomatic cover have no such immunity from prosecution".
There are also laws surrounding government and organisational intelligence and surveillance. Generally, the body involved should be issued with some form of warrant or permission from the government and should be enacting their procedures in the interest of protecting national security or the safety of public citizens. Those carrying out intelligence missions should act within not only RIPA but also the Data Protection Act and Human Rights Act. However, there are spy equipment laws and legal requirements around intelligence methods that vary for each form of intelligence enacted.
In military conflicts, espionage is considered permissible as many nations recognize the inevitability of opposing sides seeking intelligence each about the dispositions of the other. To make the mission easier and successful, soldiers or agents wear disguises to conceal their true identity from the enemy while penetrating enemy lines for intelligence gathering. However, if they are caught behind enemy lines in disguises, they are not entitled to prisoner-of-war status and subject to prosecution and punishment—including execution.
The Hague Convention of 1907 addresses the status of wartime spies, specifically within "Laws and Customs of War on Land" (Hague IV); October 18, 1907: CHAPTER II Spies". Article 29 states that a person is considered a spy who, acts clandestinely or on false pretences, infiltrates enemy lines with the intention of acquiring intelligence about the enemy and communicate it to the belligerent during times of war. Soldiers who penetrate enemy lines in proper uniforms for the purpose of acquiring intelligence are not considered spies but are lawful combatants entitled to be treated as prisoners of war upon capture by the enemy. Article 30 states that a spy captured behind enemy lines may only be punished following a trial. However, Article 31 provides that if a spy successfully rejoined his own military and is then captured by the enemy as a lawful combatant, he cannot be punished for his previous acts of espionage and must be treated as a prisoner of war. Note that this provision does not apply to citizens who committed treason against their own country or co-belligerents of that country and may be captured and prosecuted at any place or any time regardless whether he rejoined the military to which he belongs or not or during or after the war.
The ones that are excluded from being treated as spies while behind enemy lines are escaping prisoners of war and downed airmen as international law distinguishes between a disguised spy and a disguised escaper. It is permissible for these groups to wear enemy uniforms or civilian clothes in order to facilitate their escape back to friendly lines so long as they do not attack enemy forces, collect military intelligence, or engage in similar military operations while so disguised. Soldiers who are wearing enemy uniforms or civilian clothes simply for the sake of warmth along with other purposes rather than engaging in espionage or similar military operations while so attired are also excluded from being treated as unlawful combatants.
Saboteurs are treated as spies as they too wear disguises behind enemy lines for the purpose of waging destruction on an enemy's vital targets in addition to intelligence gathering. For example, during World War II, eight German agents entered the U.S. in June 1942 as part of Operation Pastorius, a sabotage mission against U.S. economic targets. Two weeks later, all were arrested in civilian clothes by the FBI thanks to two German agents betraying the mission to the U.S. Under the Hague Convention of 1907, these Germans were classified as spies and tried by a military tribunal in Washington D.C. On August 3, 1942, all eight were found guilty and sentenced to death. Five days later, six were executed by electric chair at the District of Columbia jail. Two who had given evidence against the others had their sentences reduced by President Franklin D. Roosevelt to prison terms. In 1948, they were released by President Harry S. Truman and deported to the American Zone of occupied Germany.
The U.S. codification of enemy spies is Article 106 of the Uniform Code of Military Justice. This provides a mandatory death sentence if a person captured in the act is proven to be "lurking as a spy or acting as a spy in or about any place, vessel, or aircraft, within the control or jurisdiction of any of the armed forces, or in or about any shipyard, any manufacturing or industrial plant, or any other place or institution engaged in work in aid of the prosecution of the war by the United States, or elsewhere".
Spies have long been favourite topics for novelists and filmmakers. An early example of espionage literature is Kim by the English novelist Rudyard Kipling, with a description of the training of an intelligence agent in the Great Game between the UK and Russia in 19th century Central Asia. Even earlier work was James Fenimore Cooper's classic novel, The Spy, written in 1821, about an American spy in New York during the Revolutionary War.
During the many 20th-century spy scandals, much information became publicly known about national spy agencies and dozens of real-life secret agents. These sensational stories piqued public interest in a profession largely off-limits to human interest news reporting, a natural consequence of the secrecy inherent in their work. To fill in the blanks, the popular conception of the secret agent has been formed largely by 20th and 21st-century fiction and film. Attractive and sociable real-life agents such as Valerie Plame find little employment in serious fiction, however. The fictional secret agent is more often a loner, sometimes amoral—an existential hero operating outside the everyday constraints of society. Loner spy personalities may have been a stereotype of convenience for authors who already knew how to write loner private investigator characters that sold well from the 1920s to the present.
Johnny Fedora achieved popularity as a fictional agent of early Cold War espionage, but James Bond is the most commercially successful of the many spy characters created by intelligence insiders during that struggle. His less fantastic rivals include Le Carre's George Smiley and Harry Palmer as played by Michael Caine.
Jumping on the spy bandwagon, other writers also started writing about spy fiction featuring female spies as protagonists, such as The Baroness, which has more graphic action and sex, as compared to other novels featuring male protagonists.
Espionage has also made its way into comedy depictions. The 1960s TV series Get Smart portrays an inept spy, while the 1985 movie Spies Like Us depicts a pair of none-too-bright men sent to the Soviet Union to investigate a missile.
The historical novel The Emperor and the Spy highlights the adventurous life of U.S. Colonel Sidney Forrester Mashbir, who during the 1920s and 1930s attempted to prevent war with Japan, and when war did erupt, he became General MacArthur's top advisor in the Pacific Theater of World War Two.
World War II: 1939–1945
|Mashbir, Sidney||I Was an American Spy: published 1953, republished as 65th Anniversary Edition in 2019||Horizon Productions||1953, republished 2019||American intelligence agent who played a significant role in both WWI and WWII. Colonel Mashbir is included in the Army Intelligence Corps Hall of Fame. He is a pioneer of military intelligence and is one of two men who first created the framework for the C.I.A.|
|Babington-Smith, Constance||Air Spy: The Story of Photo Intelligence in World War II||1957|
|Berg, Moe||The Catcher Was a Spy: The Mysterious Life of Moe Berg||Vintage Books||1994||— Major league baseball player and OSS Secret Intelligence (SI) spy in Yugoslavia|
|Bryden, John||Best-Kept Secret: Canadian Secret Intelligence in the Second World War||Lester||1993||—|
|Doundoulakis, Helias||Trained to be an OSS Spy||Xlibris||2014||OSS Secret Intelligence (SI) spy in Greece|
|Hall, Virginia||The Spy with the Wooden Leg: The Story of Virginia Hall||Alma Little||2012||SOE and OSS spy in France|
|Hinsley, F. H. and Alan Stripp||Codebreakers: The Inside Story of Bletchley Park||—||2001||—|
|Hinsley, F. H.||British Intelligence in the Second World War||—||1996||Abridged version of multivolume official history.|
|Hohne, Heinz||Canaris: Hitler's Master Spy||—||1979||—|
|Jones, R. V.||The Wizard War: British Scientific Intelligence 1939–1945||—||1978||—|
|Kahn, David||Hitler's Spies: German Military Intelligence in World War II||—||1978||—|
|Kahn, David||Seizing the Enigma: The Race to Break the German U-Boat Codes, 1939–1943||—||1991||FACE|
|Kitson, Simon||The Hunt for Nazi Spies: Fighting Espionage in Vichy France||—||2008|
|Leigh Fermor, Patrick||Abducting a General: The Kreipe Operation in Crete||New York Review Books||2015||SOE spy who abducted General Kreipe from Crete|
|Lewin, Ronald||The American Magic: Codes, Ciphers and the Defeat of Japan||���||1982||—|
|Masterman, J. C.||The Double Cross System in the War of 1935 to 1945||Yale||1972||—|
|Persico, Joseph||Roosevelt's Secret War: FDR and World War II Espionage||—||2001||—|
|Persico, Joseph||Casey: The Lives and Secrets of William J. Casey-From the OSS to the CIA||—||1991||—|
|Pinck, Dan||Journey to Peking: A Secret Agent in Wartime China||US Naval Institute Press||2003||OSS Secret Intelligence (SI) spy in Hong Kong, China, during WWII|
|Ronnie, Art||Counterfeit Hero: Fritz Duquesne, Adventurer and Spy||—||1995||ISBN 1-55750-733-3|
|Sayers, Michael & Albert E. Kahn||Sabotage! The Secret War Against America||—||1942||—|
|Smith, Richard Harris||OSS: The Secret History of America's First Central Intelligence Agency||—||2005||—|
|Stanley, Roy M.||World War II Photo Intelligence||—||1981||—|
|Wark, Wesley||The Ultimate Enemy: British Intelligence and Nazi Germany, 1933–1939||—||1985||—|
|Wark, Wesley||"Cryptographic Innocence: The Origins of Signals Intelligence in Canada in the Second World War" in Journal of Contemporary History 22||—||1987||—|
|West, Nigel||Secret War: The Story of SOE, Britain's Wartime Sabotage Organization||—||1992||—|
|Winterbotham, F. W.||The Ultra Secret||Harper & Row||1974||—|
|Winterbotham, F. W.||The Nazi Connection||Harper & Row||1978||—|
|Cowburn, B.||No Cloak No Dagger||Brown, Watson, Ltd.||1960||—|
|Wohlstetter, Roberta||Pearl Harbor: Warning and Decision||—||1962||—|
Cold War era: 1945–1991
|Ambrose, Stephen E.||Ike's Spies: Eisenhower and the Intelligence Establishment||—||1981–||—|
|Andrew, Christopher and Vasili Mitrokhin||The Sword and the Shield: The Mitrokhin Archive and the Secret History of the KGB||Basic Books||1991, 2005||ISBN 0-465-00311-7|
|Andrew, Christopher, and Oleg Gordievsky||KGB: The Inside Story of Its Foreign Operations from Lenin to Gorbachev||—||1990||—|
|Aronoff, Myron J.||The Spy Novels of John Le Carré: Balancing Ethics and Politics||—||1999||—|
|Bissell, Richard||Reflections of a Cold Warrior: From Yalta to the Bay of Pigs||—||1996||—|
|Bogle, Lori, ed.||Cold War Espionage and Spying||—||2001–||essays|
|Christopher Andrew and Vasili Mitrokhin||The World Was Going Our Way: The KGB and the Battle for the Third World||—||—||—|
|Christopher Andrew and Vasili Mitrokhin||The Mitrokhin Archive: The KGB in Europe and the West||Gardners Books||2000||ISBN 978-0-14-028487-4|
|Colella, Jim||My Life as an Italian Mafioso Spy||—||2000||—|
|Craig, R. Bruce||Treasonable Doubt: The Harry Dexter Spy Case||University Press of Kansas||2004||ISBN 978-0-7006-1311-3|
|Dorril, Stephen||MI6: Inside the Covert World of Her Majesty's Secret Intelligence Service||—||2000||—|
|Dziak, John J.||Chekisty: A History of the KGB||—||1988||—|
|Gates, Robert M.||From The Shadows: The Ultimate Insider's Story Of Five Presidents And How They Won The Cold War||—||1997||—|
|Frost, Mike and Michel Gratton||Spyworld: Inside the Canadian and American Intelligence Establishments||Doubleday Canada||1994||—|
|Haynes, John Earl, and Harvey Klehr||Venona: Decoding Soviet Espionage in America||—||1999||—|
|Helms, Richard||A Look over My Shoulder: A Life in the Central Intelligence Agency||—||2003||—|
|Koehler, John O.||Stasi: The Untold Story of the East German Secret Police||—||1999||—|
|Persico, Joseph||Casey: The Lives and Secrets of William J. Casey-From the OSS to the CIA||—||1991||—|
|Murphy, David E., Sergei A. Kondrashev, and George Bailey||Battleground Berlin: CIA vs. KGB in the Cold War||—||1997||—|
|Prados, John||Presidents' Secret Wars: CIA and Pentagon Covert Operations Since World War II||—||1996||—|
|Rositzke, Harry.||The CIA's Secret Operations: Espionage, Counterespionage, and Covert Action||—||1988||—|
|Srodes, James||Allen Dulles: Master of Spies||Regnery||2000||CIA head to 1961|
|Sontag Sherry, and Christopher Drew||Blind Man's Bluff: The Untold Story of American Submarine Espionage||Harper||1998||—|
|Encyclopedia of Cold War Espionage, Spies and Secret Operations||Greenwood Press/Questia||2004||—|
- Anderson, Nicholas NOC Enigma Books 2009 – Post-Cold War era
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- Animals used in espionage
- Chinese intelligence operations in the United States
- Classified information
- Clandestine operation
- Dumpster diving
- Intelligence assessment
- Flying monkeys (psychology)
- History of Soviet espionage
- Human intelligence (intelligence gathering)
- Labor spies
- List of cryptographers
- List of intelligence agencies
- List of intelligence gathering disciplines
- Military intelligence
- Operation Snow White
- Security clearance
- Jalal Haji Zawar
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