The Soviet Union ended the 1930s with a huge fleet of tanks almost completely derived from foreign designs, but before 1941 developed some of the most important trend-setting tanks of the war. The problem the Soviet tank force faced in 1941 was not primarily the technical quality of its vehicles, but the very poor state of maintenance, the appalling lack of readiness, and the poor command situation brought on by the purges of the officer class. By 1940, the Red Army had adopted an advanced combat doctrine that its command structure and tank force simply could not execute.