The 2K11 Krug (NATO code SA-4 Ganef) is a Soviet-made medium-range air defence missile. The development of the system started in 1958. The first version, Krug-A, entered service in 1967, with extensively modified versions, the Krug-M in 1971 and the Krug-M1 in 1974, which were developed to rectify problems discovered during army service. It was first unveiled during a military parade in Moscow in May 1965. Modified versions, the Krug-M in 1971 and the Krug-M1 in 1974 were developed to rectify problems discovered during army service. The 2K11 was briefly operated by the Soviet army during the war in Afghanistan in 1979 and 1980, but was withdrawn several months after the initial invasion. In 1997, it was reported that, between 1993 and 1996, some 27 fire units of Krug and 349 missiles had been sold to Armenia.
Each TEL (Transporter Erector Launcher) SA-4 Ganef 2P24 (2P24M for the Krug-M version) consists of a tracked armoured chassis on top of which is mounted a hydraulically operated turntable carrying two missiles. The launcher can be traversed through 360º and the missiles elevated up to an angle of 45º on their launcher arms for launching.
The missiles are launched with the aid of four solid fuel rocket motors inside boosters attached to the outside of the missile. Once they have burned and the missile is aloft, a liquid-fuelled ramjet sustainer engine is ignited. It reaches speeds of up to Mach 4 and has an effective range of 50-55 km (31-34 miles) depending upon the version. It carries a 135 kg (300 lb) fragmentation warhead. Possible engagement altitudes range from 100m to 27 km (330-88500 feet).