Istrebitel Sputnikov, or IS (Russian: Истребитель спутников, ИС, meaning "destroyer of satellites"^[1]), was a Soviet anti-satellite weapons programme which led to the deployment of the IS-A or I2P system during the 1970s and 1980s.^[2] IS satellites were originally intended to launch on UR-200 rockets, but following the cancellation of the UR-200, the Polyot, Tsyklon-2A and Tsyklon-2 rockets were used instead.^[3]

The first test flights of the IS spacecraft used the I1P configuration, and served to demonstrate the propulsion and control systems of the spacecraft.^[4] Both were launched by Polyot rockets, and were designated Polyot 1 and Polyot 2. They were launched on 1 November 1963 and 12 April 1964 respectively.^[3] Following this, IS-A or I2P interceptors and IS-P or I2M targets were launched. Only four IS-P targets were launched before the type was replaced by the cheaper DS-P1-M satellite,^[5] launched as part of the Dnepropetrovsk Sputnik programme. Later IS-A tests intercepted DS-P1-M satellites, or the Lira satellites that succeeded them.^[6]

• Kosmos 2499