 Beginning in July 1940 , the Red Army General Staff developed war plans that identified the Wehrmacht as the most dangerous threat to the Soviet Union , and that in the case of a war with Germany , the Wehrmacht 's main attack would come through the region north of the Pripyat Marshes into Belorussia ; which later proved to be correct . But Stalin disagreed , and in October he authorized the development of new plans that assumed a German attack would focus on the region south of Pripyat Marshes towards the economically vital regions in Ukraine . This became the basis for all subsequent Soviet war plans and the deployment of their armed forces in preparation for the German invasion . 
