The FSK (Federalnaya Sluzhba Kontrrazvedki (Федера́льная Слу́жба Контрразве́дки), Federal Counterintelligence Service) was a state security organization of the Russian Federation. The FSK was the successor organization to the KGB. It existed from 1993 to 1995, when it was reorganized into the FSB. [1]

Sources

[1] https://en.wikipedia.org/wiki/Federal_Counterintelligence_Service