The ZSU-23-4 "Shilka" is a lightly armoured, self-propelled, radar guided anti-aircraft weapon system (SPAAG). ZSU stands for Zenitnaya Samokhodnaya Ustanovka, "anti-aircraft self-propelled system". It is named after the Russian Shilka River. Its NATO reporting name is "Awl" (probably because of confusion or association with the Russian word Shilo for "awl").
