What was the reason for the retreat of the Red Army at the beginning of the war?

One of the reasons for the retreat of the Red Army during the beginning of World War II is that the country had problems with the military industry, there were few weapons and armored vehicles, and the country was economically unprepared to withstand Hitler’s well-trained, trained and equipped army. Also, these reasons include the fact that the attack on the USSR was very unexpected, the border troops were not ready to take a blow of such power and therefore retreated. The fact that the army lacked experienced officers also played a role.