Federal Security Service of the Russian Federation

The Federal Security Service of the Russian Federation is the principal security agency of Russia and the main successor agency to the Soviet Union's KGB; its immediate predecessor was the Federal Counterintelligence Service which was reorganized into the FSB in 1995. The three major structural successor components of the former KGB that remain administratively independent of the FSB are the Foreign Intelligence Service, the Federal Protective Service, and the Main Directorate of Special Programs of the President of the Russian Federation.

The primary responsibilities are within the country and include counter-intelligence, internal and border security, counterterrorism, surveillance and investigating some other types of serious crimes and federal law violations. It is headquartered in Lubyanka Square, Moscow's center, in the main building of the former KGB.

Source: Wikipedia