Why did the Soviet Union move factories eastward during the German invasion?

During the German invasion of the Soviet Union, the Soviet leadership implemented a scorched-earth policy to deny resources to the advancing enemy. As part of this strategy, entire steel and munitions plants located in the western regions of the U.S.S.R. were dismantled and transported by rail to the east.1

By relocating these industrial facilities, the Soviet Union achieved two critical objectives:
* Denial of Resources: It prevented the German military from capturing and utilizing vital industrial infrastructure for their own war effort.1
* Sustained Production: Once moved to the east, these factories were reassembled and put back into production, allowing the Soviet Union to maintain its military output and continue the war effort despite the loss of its western territories.1

This massive logistical undertaking was essential to the Soviet defense, as it preserved the industrial capacity necessary to supply the Red Army as it regrouped and eventually launched counteroffensives against the German forces.1