The Spähpanzer Ru 251 was a German light tank based on the Kanonenjagdpanzer tank destroyer, proposed to replace the M41 Walker Bulldog. During the Cold War, the Bundeswehr worked on projects like the Ru 251. In this context, the Europanzer project was launched, resulting in the development and production of the Leopard 1 for West Germany and the AMX-30 for France. In the early 1960s, the Bundeswehr still used American M41 Walker Bulldog as reconnaissance tanks. In 1960, an effort was launched to develop a new light reconnaissance tank. The Ru 251 light tank was based on the Kanonenjagdpanzer tank destroyer and is armed with the same 90 mm Rheinmetall BK 90 L/40 tank gun. Prototypes were built in 1963 and 1964. In 1964, the Ru 251 prototype went through rigorous operational trials while the Leopard 1 main battle tank was being built for serial production. Ultimately, it was decided that all resources would be directed toward the Leopard 1 main battle tank, and the Ru 251 project would be terminated.

Introduced in Update 1.67 "Assault", the Ru 251 is a light reconnaissance tank with minimal armour that is not intended for close combat. The Ru 251's armour is effective against large-calibre machine gun bursts but is vulnerable to higher-calibre fire. The Ru 251 was planned as a light reconnaissance tank, capable of moving rapidly and discreetly and attacking targets of opportunity before repositioning itself using its great mobility: any additional armour would slow the tank down. Best for medium-range engagements, but also suitable for close-range and long-range applications.