Modern Russian military special forces, GRU, SSO and PDSS in action. The GRU is Russia’s largest foreign intelligence agency. They deployed six times as many agents in foreign countries as the SVR, the successor of the KGB’s foreign operations directorate (PGU KGB). GRU also commanded 25,000 Spetsnaz troops . The SSO is a specially created unit of the Armed Forces of the Russian Federation, the formation of which began in 2009 during a large-scale reform of the Russian Federation Armed Forces (2008â€“2020). The PDSS (Russian Marine Commando) is a Russian Naval Spetsnaz unit under operational subordination to the Main Intelligence Directorate (GRU).