The V-75 SA-2 GUIDELINE is a medium to high altitude surface-to-air missile system. This two-stage missile has a large solid propellant booster stage fitted with four very large delta fins. The core stage consists of a storable liquid propellant sustainer rocket motor using inhibited red fuming nitric acid oxidizer and kerosene fuel. A set of four cropped delta-shaped wings are located near the mid-section, with a second in-line set of smaller fixed fins at the nose, and a third in-line set of slightly larger powered control fins at the tail. The guidance system at an SA-2 site can handle only one target at a time, but can direct three missiles against a target simultaneously. Additional missiles could be fired against the same target after one or more missiles of the first salvo had completed their run. The Soviets apparently believed they must program three or four missiles against each target in order to achieve acceptable kill probabilities. The 295 kg nuclear warhead used only on the SA-2E variant is believed to have a yield of 15 kT. The other V-75 variants have an internally grooved fragmentation warhead weighs 195 kg (130 kg of which is high explosive) with proximity, contact and command fusing available. This conventional warhead is fitted forward of the main fins and behind the nose-mounted guidance assembly. At medium and low altitudes the kill radius is about 65 meters and the blast radius for severe damage is 100-120 meters. The maximum blast radius against a high altitude target is approximately 250 meters, due to the rarefied atmosphere. The weapon has a accuracy of 75 meters with the large blast radius compensating for system inaccuracies. The system S-75 participated in the combat operations in Vietnam. On 01 May 1960, near Sverdlovsk, the invulnerable, high-altitude reconnaissance aircraft U-2 which was being piloted by Gary Powers was shot down by an SA-2. Although there are a variety of arrangement patterns, all sites consist of six launching positions -- usually revetted - deployed around a guidance radar and linked by service roads to facilitate loading. While the sites were permanent installations, all operating components of the system are mounted on wheeled vehicles and are capable of movement by road or raiL The V-75 was the basic missile defense system for critical urban-industrial areas in the USSR, other than Moscow. The V-75 deployment began on a wide scale since early 1958, with sites located throughout the western part of the Soviet Union and Warsaw Pact countries. Deployment patterns and levels of concentration varied according to the geography, size, and shape of the target area, and the Soviet estimate of the worth of individual targets. Between mid-1958 and 1964 more than 600 SA-2 sites were identified by US intelligence in the USSR, mostly in defense of population centers, industrial complexes, and government control centers. Most SA-2 sites defended major centers of population and industry. SA-2 defenses were also deployed for the special protection of nuclear materials production and storage facilities. In addition, some key Soviet field forces and long range bomber bases were included in the SA-2 deployment pattern. The construction of sites and the training and activation of firing units was seasonal, with activity at a minimum during the winter months. The sites in the Moscow area, located within the inner ring of SA-1 sites, were intended to supplement the existing defenses. Deployment of SA-2 installations around Moscow included seven sites as of 1964 as part of a program to supplement the SA-1 system.