HISTORY OF THE NORTH KOREAN ARMY (1952)
The origins and development of North Korea's military forces, from the vantage point of 1952, are described in a declassified U.S. Army intelligence report (large pdf).
"Although the North Korean Army was not officially activated until 8 February 1948, the backbone of the armed forces was forged in 1946 under the mask of Central Peace Preservation Units and Youth Training Organizations. Using battle-hardened Korean veterans of the Chinese Communist Forces as a core, the puppet government built a modern military force whose only glaring weakness was in a lack of air power. The striking comparison in organization, logistics and tactics of the North Korean Army with those of the Soviet ground forces is attributable to the influence of the Soviet occupation army and the multitude of advisors which were left behind upon the Red Army's withdrawal."
A digital copy of the report was made available by the Combined Arms Research Library at Fort Leavenworth, KS. See "History of the North Korean Army," U.S. Army Far East Command, July 31, 1952.