Changes

The GRU continued to be the main structure for spying after the establishment of the Soviet Union, although modified and often renamed. After the rise of the Soviet Union, various organizations were formed that took some of the earlier lessons from the GRU and secret police organizations that were used by the tsars. The first was Cheka, then People's Commissariat for State Security (NKGB), the People's Commissariat for Internal Affairs (NKVD), which was based on the GPU established in the 1920s, and Ministerstvo gosudarstvennoy bezopasnosti SSSR (MGB). These agencies often succeeded each other or overlapped, but they also generally focused on domestic and foreign espionage. Many lessons were learned by these agencies during the 1920-1940s. Sabotage and deception campaigns destabilized the White Army that supported the reestablishment of the tsar. The intelligence agencies also infiltrated Mexico to assassinate Trotsky and his supporting group, who were seen as a rivals to Stalin, and many successful war time sabotage activities were conducted. These events help make the Soviet spy networks among the most effective in internal monitoring and surpression suppression and foreign espionage.<ref>For more on Soviet spy agencies, see: Haslam, Jonathan. 2015.<i> Near and Distant Neighbors: A New History of Soviet Intelligence</i>. First edition. New York, NY: Farrar, Straus and Giroux.</ref>