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Shelter squads were also under NKVD. Those troops were established by NKVD. They consisted of armed NKVD employees, who were to follow military subdivision. They were supposed to make sure that no deserting would happen and not to let anybody in the rear. They had power to kill the running soldier on spot. Deserters were caught. Sometimes they had to go through martial court. At times they were shot depending on the circumstances. Such shelter squads were made of loyal communists and Komsomol members. They acted very ruthlessly, even too ruthlessly.
Interview
Vladimir Tseitlin