Preparations for the offensive were, however, far from perfect; on 8 November, "Stavka" issued orders to postpone the launch date of the operation, because transportation delays had prevented many units from being able to move into place. In the meantime, units at the front went through a number of war games to practice repelling an enemy counterattack and exploiting a breakthrough with mechanized forces. These movements were masked through a deception campaign by the Soviets, including the decrease of radio traffic, camouflage, operational security, using couriers for communication instead of radio, and active deception, such as increasing troop movements around Moscow. Troops were ordered to build defensive fortifications, to offer false impressions to the Germans, while fake bridges were put up to divert attention from the real bridges being built across the Don River. The Red Army also stepped up attacks against Army Group Center and set up dummy formations to maintain the idea of a main offensive against German forces in the center.