The rest of the GUGB was abolished and staff were moved to the newly created People's Commissariat for State Security (NKGB).
The Soviet security organizations were merged in July 1941, after the German invasion, with the NKGB Directorates returned to NKVD as separate units.
According to historian John Dziak 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 manpower in the security administration.
Other reasons Dziak 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.