The KGB

In the 1980s, the glasnost liberalisation of Soviet society provoked KGB Chairman Vladimir Kryuchkov (1988–91) to lead the August 1991 Soviet coup d'état attempt to depose President Mikhail Gorbachev. The thwarted coup d'état ended the KGB on 6 November 1991.
In the late Cold War, the KGB was successful with intelligence coups in the cases of the mercenary walk-in recruits FBI counterspy Robert Hanssen (1979–2001) and CIA Soviet Division officer Aldrich Ames (1985–1994).
KGB, Russian in full Komitet Gosudarstvennoy Bezopasnosti, English Committee for State Security, foreign intelligence and domestic security agency of the Soviet Union. During the Soviet era the KGB’s responsibilities also included the protection of the country’s political leadership, the supervision of border troops, and the general surveillance of the population.
Pre-KGB Soviet Security Services: Established in 1954, the KGB was the most durable of a series of security agencies starting with the Cheka.