9M31

The 9M31 is a Soviet-era surface-to-air missile system. It was developed by the Fakel Machine-Building Design Bureau and entered service in the early 1960s. The 9M31 was part of the SA-3 Goa missile system, also known as the S-125 Neva. This missile was designed for engaging low to medium altitude aircraft.

The 9M31 missile is a two-stage solid-propellant rocket. It features a radio command guidance system, meaning it is guided by ground-based radar that transmits commands to the missile in flight. The warhead is typically a high-explosive fragmentation type. The missile has a length of approximately 6.08 meters and a diameter of about 0.65 meters. Its launch weight is around 947 kilograms. The operational range of the 9M31 missile is approximately 35 kilometers, with an engagement altitude ceiling of around 18,000 meters.

The SA-3 Goa system, which utilizes the 9M31, was designed as a complementary air defense system to the SA-2 Guideline (S-75). While the SA-2 was intended for higher altitude targets, the SA-3 was optimized for lower-flying threats, such as tactical aircraft and helicopters. The system was widely exported and saw service with numerous countries around the world. Over its service life, the 9M31 and its associated guidance systems underwent several upgrades and modifications to improve performance and counter evolving threats. Despite its age, the SA-3 Goa system, and by extension the 9M31 missile, remained in service with some air defense forces for a considerable period.