Development of the A-20 tank started at Kharkov Factory No. 138 in December 1937. The project was a further development of the BT-7 tank and became a predecessor of the legendary T-34. Work on the vehicle was led by Mikhail Koshkin. On May 18, 1938, technical characteristics of the tank designated BT-20 were approved. Only a few experimental prototypes, with a wheeled caterpillar suspension, were built for training purposes.