North Koreans are getting shorter from shortages in food. Lack of nutrition is causing poor growth during the period of growth, making North Koreans shorter and small.
Due to this phenomenon, North Korea has changed the conscriptioin standards.
In 2008, the limit was 150cm, and 48kg, but from this March, the limit was changed to 142cm.

North Korean soldiers have the physique of elementary students.
Machine guns are 1m long in average. I wonder how a 140cm tall soldier can carry and handle a weapon more than half his height.It's been told that the North Korean regime is encouraging its people to exercise, but without nutrition and food supply, all the efforts are deemed to be fruitless. It's pathetic that the North Koreans are unable to see the fundamental problem, and going off topic.

(Nation & World | Effects of famine: Short stature evident in North Korean generation | Seattle Times Newspaper)