The KGB (Komitet Gosudarstevenny Bezopasnosti), Committee for State Security was the Soviet Union's (U.S.S.R) chief security and intelligence organization during the cold war.  Their operations were similar to those of the United States CIA.  With the end of the Cold War, KGB was cut from the budget.  The GRU's (Glavnoe Razvedyvatelnoe Upravlanie), Main Intelligence Organization, duties roughly correspond to the US Defense Intelligence Agency. They have no internal security functions, but great many activities in foreign areas of operation.  The GRU is in control of SPETSNAZ troops and their covert operations.  Sergei Golovko is the present head of the GRU.
