to animals on or in the vicinity of the runway. Ethiopian soldiers interpreted these facts as indicative of a suicide plane looking to strike targets within the base camp, and responded with fire. Variants and upgrades Soviet Union/Russian Federation ZU-23M – Upgraded variant, designed by the Nudelman Precision Engineering Design Bureau (KB Tochmash). Has new targeting system (which includes laser rangefinder, television channel, optical mechanic device, can be reinforced with thermo location channel and a television system for usage at night) and electromechanic turn system. Optionally, the mount can be fitted with two short-range air-defence missiles, such as the 9M32M "Strela-2M" or the 9M39 "Igla". ZU-23M1 – This is the current model, developed by Open Joint Stock Company Podolsky Electromechanical Plant of Special Engineering "PEMZ Spetsmash" and Closed Joint Stock Company "NTC Elins" and offered by Rosoboronexport. Like the ZU-23M, it has an upgraded fire control system and can optionally be fitted with two launchers for the "Igla" series missile, usually the 9M342 "Igla-S". The complete air-defence gun/missile system is called ZU-23/ZOM1 (often erroneously called "ZU-23/30M1"). It consists of the "missile-gun firing module" (strel'bovoj modul) ZU-23/ZOM1-SM; the "missile-launching module" (puskovoj modul) ZU-23/ZOM1-PM armed with four 9M333 "Strela-10" missiles; a remote control module (modul distantsionnogo upravleniya) ZU-23/ZOM1-MU and a portable generator AB-1. Depending on the wishes of the client, the system can be delivered without the -SM module (ZU-23/ZOM1-1), without the -PM module (ZU-23/ZOM1-2), without the remote control (ZU-23/ZOM1-3), or without -PM and -MU modules (ZU-23/ZOM1-4). The latter can be carried by the Samum 4x4 wheeled chassis vehicle and the first export contract has been signed as of early 2019. Poland ZU-23-2 – Polish designation for basic gun variant. Manufactured under license in Zakłady Mechaniczne "Tarnów" S.A. (ZMT Tarnów) since 1972. ZUR-23-2S Jod – Polish variant with electro-optical sight GP-1R and twin launcher for Strela-2M missiles, used from 1988. ZUR 23-2KG Jodek-G – Development of ZUR-23-2S with more advanced reflex sight CKE-2 (later CP-1 night-and-day sight with laser rangefinder), electromechanic gun turn system and twin launcher for Grom missiles, produced from 2002. ZUR-23-2KG-I – Improved export version for Indonesia with CKE-2I sight. TR-23-2 – Training simulator version of the ZUR-23-2KG-I. The set consists of an instructor's station and a gunner's station (a modified "artillery-missile unit" with the sight replaced by a computer station). Both stations are linked by a wireless network. ZUR 23-2SP Jodek-SP – Version used in PSRA Pilica VSHORAD