The USSR vigorously prepared the Red Army to repulse possible aggression by Germany and its allies.

The leadership of the Soviet People’s Commissariat of Defence changed after the Winter War. K. Voroshilov was replaced by S. Timoshenko, while Chief of the General Staff B. Shaposhnikov was succeeded by K. Meretskov. Many former members of the Red Army command returned to their positions, the best-known among them was the future Marshal of the Soviet Union K. Rokossovsky.

In 1940–1941, new plans for the mobilization and deployment of the armed forces were elaborated by the General Staff of the Red Army. In the western theatre of operations, the main emphasis of military planning shifted from the western to the southwestern strategic direction. Contrary to the opinion of Marshal B. Shaposhnikov, J. Stalin instructed that the weaker Balkan allies of Germany be attacked first in order to deprive the latter of its ‘key economic bases’ in the Balkans before dealing with the Third Reich as the leader of the coalition and the USSR’s strongest opponent.

The high command of the Red Army met in Moscow in late December 1940 to discuss the current state and future development of the military capacity of troops, topical issues in the theory and practice of warfare, and the experience of already waged campaigns of World War II. In January 1941, two strategic military exercises were conducted with the help of maps to give the high command of the Red Army experience in front-line and army operations. the results of the exercises led J. Stalin to replace K. Meretskov by G. Zhukov as Chief of the General Staff of the Red Army.