Suvorov offers as another piece of evidence the extensive effort Stalin took to conceal general mobilization by manipulating the laws setting the conscription age. That allowed Stalin to provide the expansive build-up of the Red Army. Since there was no universal military draft in the Soviet Union until 1939, by enacting the universal military draft on 1 September 1939 (the date World War II had begun), and by changing the minimum age for joining the Red Army from 21 to 18, Stalin triggered a mechanism which achieved a dramatic increase in the military strength of the Red Army.