Security Service, also called MI5, is a British government agency responsible for counterespionage activities within the United Kingdom. Counterespionage efforts seek to prevent the theft of a government’s secret information and to detect the presence of enemy spies.
The British government created the Secret Service Bureau in 1909. The bureau had two divisions—the Home Section, which became the Security Service, and the Foreign Section, which became the Secret Intelligence Service (also called the SIS or MI6). The initials MI in the names MI5 and MI6 originally stood for Military Intelligence. The numbers 5 and 6 represented the individual sections of the British War Office. The Foreign Section was responsible for gathering information about foreign governments. In addition to its counterespionage activities, the Home Section also served as a mediator between several groups, including British spies, the British War Office, and the Admiralty, which commanded the Royal Navy.
Prior to World War I (1914-1918), the Home Section tracked down German intelligence agents in the United Kingdom. During the war, it arrested over 50 suspected enemy spies. In 1931, it was renamed the Security Service.
Many of the Security Service’s early activities focused on threats posed by the Soviet Union. By the late 1930’s, however, Germany had replaced the Soviet Union as the chief target of Security Service activities. During World War II (1939-1945), the service’s efforts led to the arrest of numerous German spies. Instead of killing all captured spies, however, the Security Service turned some of them into double agents. Double agents pretended to work for the Germans while actually working for the British against the Germans.
The Security Service was also active during the Cold War—a period from the late 1940’s to the early 1990’s that was marked by tensions between Communist and non-Communist nations. However, a number of the agency’s operations during this time proved unsuccessful. The service also discovered that several of its key employees had been working secretly for the Soviet Union. The Security Service has also been involved in efforts to detect, prevent, and recover from terrorist activity in the United Kingdom.
