The ZU-23-2 AA Ant-aircraft gun, also known as ZU-23, is a Soviet towed 23 mm anti-aircraft twin autocannon. ZU-23-2 was developed in the late 1950s. It was designed to engage low-flying targets at a range of 2.5 km as well as armoured vehicles at a range of 2 km and for direct defense of troops and strategic locations against air assault usually conducted by helicopters and low-flying airplanes. Development of this weapon into a self-propelled anti-aircraft gun (SPAAG) lead to the ZSU-23-4 Shilka