Espionage has been around for thousands of years. The motives for espionage are still identical to those of antiquity, but the structures in which agents and spies operate have evolved considerably. Today, intelligence services are highly specialised state institutions whose portfolio often includes more than just espionage.
Intelligence services have a wide range of tasks that vary greatly depending on the nation. The primary aim is to collect and analyse political, economic or military information. Both human agents and modern technology are used in the process.
The results of this information gathering regularly form the basis for important decisions, for example in the political sector, in military operations and also in scientific or economic developments.
Other areas in which intelligence services are deployed include counter-terrorism and counter-espionage in their own country. Depending on the government’s interpretation of which groups of people are categorised as a threat to the state, sometimes far-reaching surveillance and even suppression measures against unpopular sections of the population are used.
Depending on the political circumstances, individual intelligence agencies also carry out actions of political influence, sabotage and even kidnappings or assassinations.
Intelligence agencies collect information, both public and top secret (symbolic image, Source: TayebMEZAHDIA via PixaBay)
Formerly NSA, now BND: radar domes for detecting satellite signals in Bad Aibling, Bavaria, Germany (Source: stux via Pixabay)
HUMINT
Humans Intelligence – information gathering through human sources (spies, confidential informants etc. collect information)
OSINT
Open Source Intelligence – gathering information from openly accessible (i.e. non-secret) sources (analysing reports on the Internet, newspapers, radio, etc.)
SIGINT
Signals Intelligence – information gathering through telecommunications and electronic reconnaissance (interception of radio waves, satellite transmission, cable transmission, etc.)
IMINT
Imagery intelligence – information gathering through imaging reconnaissance (images taken by aircraft, satellites or drones using optical or sensor technology)
Although there are numerous reports of espionage up to modern times, there is no institution operating in the sense of a modern intelligence agency. These were often the institutiones of rulers or the military, whose responsibilities lay in the general administrative or communicative area, and which then spied in addition to their main tasks.
The black chambers appointed by the French kings from the 15th century onwards took on specific espionage tasks. These were used for the targeted surveillance of postal traffic. However, the oldest secret service in the world is considered to be the English intelligence service, which operated in the 16th century under the reign of Queen Elizabeth I. It had a Europe-wide network of agents and high-calibre cryptography experts.
From the end of the 19th century onwards, many intelligence structures were mainly found at military level. The British Secret Service Bureau, founded in 1909, is regarded as the first official intelligence service and thus the forerunner of today’s modern intelligence services. It is the forerunner of the British secret services MI5 and MI6. During the 20th century, there was a strong increase and professionalisation of intelligence work, particularly in the course of the two world wars.
Francis Walsingham headed the English intelligence service under Queen Elizabeth I. (Source: Oil painting, around 1587, via Wikimedia Commons)
Explosion in the presidential palace in Chile: The CIA supported the military coup against the socialist head of government Allende in 1973 (Source: Biblioteca del Congreso Nacional, CC BY 3.0 CL, via Wikimedia Commons)
During the Cold War, the Soviet KGB became the largest intelligence service in history with almost 480,000 employees. In relation to the sheer size of the country’s population, the East German Stasi was the largest secret service in history with around 100,000 full-time and 98,000 unofficial employees.
The operations of the intelligence services repeatedly had a considerable influence on the course of history. This also includes various assassinations and government overthrows, which were mainly carried out by the CIA and KGB during the Cold War. At the time, these two intelligence services were among the most powerful and dangerous in the world.
Due to the immense increase in global communications, their surveillance played an increasingly important role in the intelligence world over the course of the 20th and 21st centuries. The best intelligence services in this field are the American NSA and the British GCHQ, but increasingly also the Chinese secret service.
But even in the digital world, the oldest espionage tool, the human agent, still plays an important role. Good intelligence services do not rely on a single type of information gathering, but utilise all available resources to collect, compare and evaluate the collected data from as many perspectives as possible.
There are numerous criteria by which intelligence services can be assessed. However, it is difficult to make definitive statements about which intelligence service was or is the best, most powerful, most dangerous and largest.
This is also due to the fact that many intelligence services have specialised in certain aspects of espionage, which means that the work of the intelligence services is often very different and difficult to compare in general. In addition, the work of many intelligence services cannot be conclusively evaluated at present due to the secrecy associated with their work.
We present a selection of the world’s most important historical and current intelligence services to provide some orientation:
Nation: Germany
Foundation: 1950
Function: Domestic intelligence service
Headquarters: Cologne
Employees (2022): approx. 4,400
Nation: Germany
Foundation: 1956
Function: Foreign intelligence service
Headquarters: Berlin
Employees (2024): approx. 6,500
Nation: USA
Foundation: 1947
Function: Foreign intelligence service
Headquarters: Langley, Virginia
Employees (2019): approx. 21,500
Nation: USA
Founded: 1908
Function: Domestic intelligence agency, law enforcement agency
Headquarters: Washington, D.C.
Employees (2013): approx. 36,000
Nation: Russia
Founded: 1995
Function: Domestic intelligence agency, secret police
Headquarters: Moscow
Employees (2023): approx. 350,000
Nation: United Kingdom
Foundation: 1919
Function: Intelligence and Security Service (SIGINT)
Headquarters: Cheltenham
Employees (2021): approx. 7,180
Nation: Russia
Foundation: 1918
Function: Military intelligence
Headquarters: Moscow
Employees (2024): approx. 12,000
Nation: China
Foundation: 1983
Function: Domestic and foreign intelligence service, security service, secret police
Headquarters: Beijing
Employees (2020): approx. 110,000
Nation: Israel
Foundation: 1949
Function: Foreign intelligence service
Headquarters: Tel Aviv
Employees (2018): approx. 7,000
Nation: USA
Foundation: 1952
Function: Foreign intelligence service (SIGINT)
Headquarters: Crypto City, Maryland
Employees (2013): approx. 40,000
Nation: United Kingdom
Foundation: 1909
Function: Foreign intelligence service
Headquarters: London
Employees (2021): approx. 3,644
Nation: United Kingdom
Foundation: 1909
Function: Domestic intelligence service
Headquarters: London
Employees (2021): approx. 5,250
Nation: German Reich
Foundation: 1928 / Dissolution: 1944
Function: Military intelligence service
Headquarters: Berlin
Employees (1939): approx. 2000
Nation: German Democratic Republic (GDR)
Founded: 1950, dissolved: 1990
Function: Domestic and foreign secret service, secret police
Headquarters: East Berlin
Employees (1988): approx. 100,000 full-time employees, approx. 189,000 unofficial employees (IMs)
Nation: Soviet Union
Founded: 1917, disbanded: 1922
Function: Secret police
Headquarters: Petrograd (St Petersburg), Moscow
Employees (1921): approx. 200,000
Nation: Soviet Union
Foundation: 1954 / Dissolution: 1991
Function: Domestic and foreign intelligence service, secret police
Headquarters: Moscow
Employees (1991): 480,000
A intelligence agency is an institution that usually works for a government. Its primary aim is to collect and analyse political, economic or military information. Other areas in which intelligence services are deployed include counter-terrorism and counter-espionage, as well as political influence operations, sabotage and even kidnappings or assassinations.
Everyone knows the British foreign intelligence service MI6 from James Bond, while the Soviet KGB, the American CIA and the German Stasi are best known from the Cold War. Edward Snowden’s revelations have made the American secret service NSA world-famous.
Germany has the Federal Office for the Protection of the Constitution (BfV) as its domestic intelligence service, the Federal Intelligence Service (BND) as its foreign intelligence service and the Military Counterintelligence Service (MAD) as its military intelligence service. Each federal state also has its own intelligence service, the Office for the Protection of the Constitution.