In the early 1960s the German Leopard 1 and the US M60 were the newest main battle tanks in their respective country's service. While designed to counter the T-54/55 tanks, it became clear that the next generation of Soviet tanks would have increased firepower and protection, and both designs would be placed at a disadvantage by the new smoothbore gun in the T-62. An upgrade project for the Leopard was planned,[1] but it appeared this model would not be enough of an advance to be worthwhile.