The FSB (Federal Security Service) is a domestic state security agency of the Russian Federation and the main successor of the Soviet Cheka, NKVD, and KGB. Its headquarters are in Lubyanka Square, Moscow.
FSB is engaged mostly in domestic affairs, while the espionage duties were taken over by the Russian Foreign Intelligence Service (former First Chief Directorate of the KGB). However FSB also includes the FAPSI agency, which is involved in electronic surveillance abroad. In addition, FSB operates freely at the territories of the former Soviet republics, and it can conduct anti-terrorist military operations anywhere in the World if ordered by the President, according to the recently adopted terrorism law. All law enforcement and intelligence agencies in Russia work under guidance of FSB if needed. For example, GRU, spetsnaz and Internal Troops detachments of Russian Ministry of Internal Affairs work together with FSB in Chechnya.