The word Cheka is an acronym of sorts for the All-Russian Extraordinary Commission for Combating Counter-Revolution and Sabotage. The word "Extraordinary" implies a certain temporary quality to the Cheka that, though its creators may have firmly believed it would be at the time, it evolved many times and even though it was even officially dissolved in 1991, the legacy of the Cheka and the KGB is as active as ever in the government of the Russian Federation.
"The Commission itself...outlined its duties as follows: To cut off at the roots all counterrevolution and sabotage in Russia; to hand over to the revolutionary court all who are guilty of such attempts; to work out measures for dealing with such cases; and to enforce these measures without mercy. It was necessary to make the foe feel that there was everywhere about him a seeing eye and a heavy hand ready to come down on him the moment he undertook anything against the Soviet Government."*
One of the reasons that the state security services of the Soviet Union were so effective whether as the Cheka, the (O)GPU, GUGB, NKGB, MGB or KGB (with a little help from the NKVD/MVD), was the fanaticism of its earliest members and their leadership. It was relatively easy to attract young, bright people to the cause of the Soviet state because so many of the intelligentsia worldwide were drawn to the romanticized notions, ideals and goals presented by the leadership of the Soviet Union. As with the French Revolution, there were numerous sympathizers and members of the working classes - or proletariat - who looked upon the November Revolution as perhaps a better way of life after the end of WWI when the world had lost its innocence on the battlefield. It was not difficult for the Cheka and the GPU/OGPU to persuade or simply recruit citizens of many European countries, particularly in England as spies, or agents provocateur, and it was even less problematic to establish "front" organizations such as the Communist International (Comintern) in countries throughout the world. Granted, not all members of the Comintern were also members of the state security services, but in terms of foreign policy, their goals were the same - eliminate or at least weaken any opposition to the Communist ideals. With idealists who converted to Communism with a fervor such as the Cambridge Five, the Soviets got a significant lead over other countries in the eventual game of "spy versus spy" that we know today. In fact, it was not until several years after WWII that the United States even formed a peacetime foreign intelligence service - the Central Intelligence Service in 1947 with the National Security Act. By then, however, the MGB (soon to be KGB) was already running scores of "illegals" or undercover agents in governments around the world, and in particular in the US and UK.
In 1922 Lenin proposed a resolution to the Tenth Party Congress that banned all factions within the Communist Party on the grounds that they only weakened the overall effectiveness of the Party. When the resolution was passed, Lenin was free to dictate policy as he felt fit. As the leader of the new country, a union of republics with Russia at the helm, Lenin rose to the status of a superior being especially after his death in 1924 and his cult of personality remained central to Soviet policy and propaganda alike until the dissolution of the Soviet Union in 1991. However, starting in 1922, the Cheka was renamed the GPU (State Political Directorate) of the NKVD (People's Commissariat for Internal Affairs) of the RSFSR (Russian Soviet Federative Socialist Republic) for nearly two years before being converted to the All-Union State Political Directorate which was separate from the NKVD and operated across the entire USSR which was founded in December 1922. Though officially the GPU had fewer powers than the Cheka, losing the power of arrest and trial, the OGPU regained all of the power of the Cheka and then some. The jurisdiction of the OGPU overshadowed all other local or republic level authorities until Stalin had it re-subordinated to the NKVD in 1934.
Propaganda poster depicting how the GPU would strike down
The NKVD became Stalin's personal army used to sway the minds of anyone who might have a political opinion that differed from his. The NKVD began what is known as the "Great Purge" or "Great Terror" which lasted from 1936-1938 and cost millions of people their lives, even founding members of the Communist Party and those closest to Stalin, including his own appointed heads of the NKVD - Genrikh Yagoda, then Nikolai Yezhov and finally Lavrenty Beria. All three of these men were the most powerful members of the regime other than Stalin himself, which is perhaps why they did not remain in Stalin's favor for very long (although Beria was arrested and executed shortly after Stalin's death under the lesser known Premier Georgy Malenkov who lost a power struggle two years later in 1955 to Nikita Krushchev). This period of Soviet history and the NKVD abuses of power is regarded by many as the lowest point in terms of ethical and humane treatment of citizens and soldiers alike. An unknown number of millions were arrested and either locked up in asylums as mentally ill or were sent to the rapidly growing number of labor camps or Gulags mostly in Siberia where conditions were such that many did not survive their incarceration. And most unfortunately, a large number of those arrested and tried by NKVD "troikas" (three judge tribunals) were executed at the hands of their captors and often at the direct order of Stalin. It was during these two years prior to the Soviet Union's involvement in WWII that nearly everyone lived in fear of being arrested by the secret police (NKVD) in the middle of the night and taken from their families only to be interrogated, tortured and otherwise coerced into making "confessions" of their crimes against the state, and either executed or exiled. The threat was real and citizens were encouraged to report suspicious behaviors of their neighbors, friends and families, and sometimes this was done as a sort of preemptive strike to divert the NKVD's attention away from themselves. Everyone lived in a constant state of fear of undercover NKVD agents and even their fellow citizens who might report them if they said the wrong thing, even as a joke. This level of paranoia and terror was so intense that to this day residents of the thousands of apartment buildings in Moscow keep an eye on each other and telephone operators are encouraged to listen in on private conversations and report any conversations of a suspicious or illegal nature, often with a monetary reward for doing so.
*Source: James Bunyan and H.H. Fisher, ed., Bolshevik Revolution, 1917-1918; Documents and Materials (Stanford: Stanford University Press; H. Milford, Oxford University Press, 1934), pp. 295-296. http://www.soviethistory.org/index.php?page=article&ArticleID=1917latsis1&SubjectID=1917security&Year=1917