The MBT-70 (German: KPz 70) was a 1960s German-U.S. joint project to develop a new main battle tank, which was to be equipped with a number of advanced features. It utilized a newly developed hydropneumatic "kneeling" suspension and housed the entire crew in the large turret. The MBT-70 was armed with a 152mm XM150 gun/launcher, which could use conventional ammunition and the Shillelagh missile for long range combat.
By 1969 the project was well over budget and Germany withdrew from the effort. They developed a new main battle tank on their own, the Leopard 2. In the US, MBT-70 development continued for a short time, until 1971 when Congress cancelled the program. They began development of a less expensive design, which became the M1 Abrams. Although the MBT-70 failed to enter service, the Leopard 2 and M1 are the current main battle tanks of both countries.
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, but it appeared this model would not be enough of an advance to be worthwhile.