This article explores the militarisation of the North Korean police and the establishment of specialised units, including the Railroad and Maritime Police, and the Korean-Manchurian border guard. The analysis primarily draws from unpublished Soviet archival material. Contrary to the assumption that strengthening the North Korean police under Soviet military administration was aimed at providing a backbone to the North Korean regime, our examination reveals that, at least initially, it was driven by the urgent need to address immediate challenges in public security. The initial crisis arose with anti-trusteeship protests and worsened when the Soviets initiated land reform, coinciding with a series of terrorist attacks against North Korean politicians and Soviet military units. The article also sheds light on the background processes that led to the creation of specialised police units such as the Railroad Police and the Maritime Police. Contrary to common perceptions, these units were not designed to become military units from the outset. Soviet documents clearly reveal that their primary function was to assist the Soviets in guarding the North Korean railroad and coastline. The Soviets initiated and controlled the establishment of the Korean-Manchurian border guard to address issues on the northern border of Korea.