The Committee for State Security (Russian: Комитет государственной безопасности, romanized: Komitet gosudarstvennoy bezopasnosti, IPA: [kəmʲɪˈtʲed ɡəsʊˈdarstvʲɪn(ː)əj bʲɪzɐˈpasnəsʲtʲɪ]), abbreviated as KGB (Russian: КГБ, IPA: [ˌkɛɡɛˈbɛ]; ) was the main security agency of the Soviet Union from 1954 to 1991. It was the direct successor of preceding Soviet secret police agencies including the Cheka, OGPU, and NKVD. Attached to the Council of Ministers, it was the chief government agency of "union-republican jurisdiction", carrying out internal security, foreign intelligence, counter-intelligence and secret police functions. Similar agencies operated in each of the republics of the Soviet Union aside from the Russian SFSR, where the KGB was headquartered, with many associated ministries, state committees and state commissions.
The agency was a military service governed by army laws and regulations, in the same fashion as the Soviet Army or the MVD Internal Troops. While most of the KGB archives remain classified, two online documentary sources are available. Its main functions were foreign intelligence, counter-intelligence, operative-investigative activities, guarding the state border of the USSR, guarding the Soviet leadership, preserving the security of government communications as well as combating dissident and separatism within Soviet society.