The M551 "Sheridan" AR/AAV was a light tank developed by the United States and named after General Philip Sheridan, of American Civil War fame. It was designed to be landed by parachute and to swim across rivers. It was armed with the technically advanced but troublesome M81/M81 Modified/M81E1 152 mm gun/launcher, which fired both conventional ammunition and the MGM-51 Shillelagh guided anti-tank missile.

A reconnaissance vehicle, also known as a scout vehicle, is a military vehicle used for forward reconnaissance. Both tracked and wheeled reconnaissance vehicles are in service. In some nations, light tanks such as the M551 Sheridan and AMX-13 have also been used by scout platoons. Their armament ranges from a medium machine gun to a large cannon. Modern examples are often fitted with ATGMs and a wide range of sensors.