The Ministry for State Security (German: Ministerium für Staatssicherheit, pronounced [minɪsˈteːʁiʊm fyːɐ̯ ˈʃtaːtsˌzɪçɐhaɪ̯t]; abbreviated MfS), commonly known as the Stasi (pronounced [ˈʃtaːziː] , an abbreviation of Staatssicherheit), was the state security service and secret police of East Germany from 1950 to 1990. The function of the Stasi in East Germany (the GDR) resembled that of the KGB in the Soviet Union, in that it served to maintain state authority and the position of the ruling party, in this case the Socialist Unity Party of Germany (SED).
https://en.wikipedia.org/wiki/Stasi