Five of these had been completed by the spring of 1956 and were undergoing preflight tests when the entire program was canceled on 13 April 1956 and all components in preparation scrapped. A week later, the Attack Aviation branch of the VVS was superseded by the Fighter-Bomber branch and the doctrine of the VVS was drastically modified. No longer would the VVS provide close support to the Army, but rather it would use tactical nuclear weapons as part of the nuclear battlefield.