The BT tanks were a series of Sovietlight tanksproduced in large numbers between 1932 and 1941. They were lightly armoured, but reasonably well-armed for their time, and had the best mobility of all contemporary tanks. The BT tanks were known by the nicknameBetkafrom theacronym, or its diminutiveBetushka. The successor of the BT tanks would be the famousT-34medium tank, introduced in 1940, which would replace all of the Soviet fast tanks,infantry tanks, andmedium tanksin service.