Changes 1941/1943
The Soviet security organizations were merged in July 1941, after the Axis invasion, with the NKGB returned to NKVD as GUGB. During 1943 the Main Directorate of State Security (or GUGB) once again became a separate administration, NKGB. These organizational changes were never explained. According to historian, John Chekisty, they may have had something to do with the Soviet occupations of Latvia, Lithuania, Estonia, eastern Poland, part of Romania (Bessarabia and northern Bukovina). Also, the numbers of apprehensions, deportations, executions and establishments of Gulags had quickly grown, which required a reorganization of structures and a boost of man power in the security administration. Other reasons Chekisty states are: the shock caused by the German aggression and the fast progress of their army; and when the Soviet victory in Stalingrad had made prospects of the recovery of previous war losses more likely.
Read more about this topic: People's Commissariat For State Security