The Research Institute of Military Sciences and Technologies of the Vietnamese People's Army carried out work on the modernization of Soviet-made ZSU-23-4M Shilka self-propelled anti-aircraft guns. The ZSU-23-4M "Shilka" was equipped with a digital optical-electronic fire control system with an automated target tracking system in both day and night conditions and a laser range finder. The optical-electronic station was created by the Vietnamese company Viettel Military Industry and Telecoms Group. It was previously reported that the ZSU-23-4M "Shilka" was supposed to be equipped with double launchers for Russian-made "Igla" MANPADS, but so far the ZSU-23-4M is without them.