Developed by the Soviet Union in the 1960s, this self-propelled system is named for its four AZP-23 cannon and nicknamed the Shiika. The Model 1977 is the ninth and final version of this system. Designed so that one, two or four cannons could be fired, this system provided low-level cover for armored and mechanized divisions. The Shiika displayed at Memorial Field saw service with the Iraqi Army during Operation Desert Storm, and was found abandoned west of Kuwait City.The Russian SP-QuadDesigned to replace the faltering ZSU-57-2, the 23-4 was designed to cater to a growing list of demands for a rapid-fire, self-propelled, high-capacity, anti-aircraft gun. The Shiika (also known as Zeus) was designed with multiple configurations. This included a single, double, and quad barrel design. The one displayed at Memorial Field is a quad barrel design and uses 23MM guns, hence the 23-4 model designation.Fitted with a built-in radar system, the Shiika was the natural replacement for aging Soviet technology that relied on visual confirmation of an enemy before firing. The first ZSU-23 was introduced in the mid-1960s, and gradually replaced the larger ZSU-57-2. Replacement was completed sometime in the 1970s. About 4,000 ZSU-23-4's were delivered to Soviet forces, while most of the 2,500 others built were deployed to other operators within the Warsaw Pact.Despite its aging design, the Shiika continues to serve in many nations across Eastern Europe, the Middle East, and North Africa. The most recent conflicts it has been used in include civil wars in Libya and Syria, and fighting in eastern Ukraine. ZSU-23-4s remain in service in Russia, Iran, Iraq, and Syria, with some obtained by the Islamic State group. Other ZSU-23-4s were captured during deployments with other opponents. Of these captured, about 60 were obtained by Israel, with another 20 or more captured by the United States. While some of these captured weapons are used occasionally for testing and training purposes, most are now on static display across the U.S.