THE US ICBM PROGRAMME
Snark and Navaho
In the immediate post-war years the feeling in the United States was that ballistic missiles offered the best long-term solution for strategic warfare, but that the technology of the time did not appear to make it possible to build a missile with the necessary range (9,300 km) and capable of carrying a nuclear payload, which at that time was large and heavy, weighing some 3 tonnes. The Convair company flight-tested the intercontinental-range MX-774 missile in 1948, but the newly independent US air force decided to follow the path pioneered by the German V-1 ‘flying bomb’ and to develop cruise missiles instead.
The first of these was the N-69 Snark pilotless bomber, which was much larger than the V-1 and had a range of 10,200 km, cruising at a height of some 12,000 m and using a star tracker to update its inertial navigation system. Its speed of 990 km/h meant, however, that, at its extreme range, it took some eleven hours to reach the target. The nose-cone carried a 5 MT (later 20 MT) nuclear warhead, and the missile could approach the target from any direction and at any height, while its very small radar cross-section made it difficult to detect. The Snark entered service in 1957 but was retired in 1961, when the Atlas ballistic missile became operational; its main significance was that it was the first operational missile to bring one superpower within attacking range of the other.
Snark was due to be succeeded by the SM-64A Navaho, a vertically launched, winged cruise missile, which travelled at Mach 3.25 (3,500 km/h) at a height of 18,300 m. Navaho would almost certainly have proved a highly effective strategic weapon, but it never reached production, as the USAF had already transferred its attention to ICBMs.
Redstone and Jupiter
Development of long-range ballistic missiles in the United States in the immediate post-war years was erratic, to say the least. The US army had obtained the plans for the A-4 (V-2) and assembled a number of former German scientists, including Werner von Braun, at the Redstone Arsenal. Their first product was the Redstone short-range (400 km), land-mobile, liquid-fuelled, nuclear-armed missile, which was in service from 1958 to 1963. Next the army started to develop the Jupiter, which was again a land-mobile missile system, but this time with a range of 2,400 km. This was midway through development when, in late 1956, the secretary of state for defense ordered that the US air force was to assume responsibility for all missiles with a range greater than 200 nautical miles (370 km). Development was completed by the USAF, and Jupiter subsequently saw limited service with the air force.
Having been concentrating on long-range cruise missiles, the USAF now had to make up for a lot of lost ground. Despite having been handed the perfectly acceptable Jupiter by the army, it initiated a very expensive crash programme for its own IRBM, leading to the Thor. This did nothing that Jupiter could not already do, but operated from a fixed base, rather than from a mobile platform. Thor’s 2,700 km range, however, was insufficient for the missile to be launched against the USSR from the continental USA, so it was handed over to the UK air force, which deployed sixty missiles between 1959 and 1964.
The entire Thor storage-and-launch complex was above ground in unprotected shelters, and the missile had be towed out to the launch pad, raised to the vertical, fuelled, prepared, and then launched, the whole process taking fifteen minutes. This was all done in the open, on concrete hard-standing, at well-documented sites, and was very vulnerable. No cost-effective measure to reduce the reaction time could be found, so the missile was phased out after only five years of service.
Meanwhile, the USAF’s major development effort had turned to the Atlas missile, which was much larger and was a true ICBM, with a range of 14,000 km. Atlas benefited from much of the technology which had been developed for the Navaho cruise missile, and entered service in 1960.
The first USAF squadron equipped with the Atlas missile used an almost identical siting system to Thor, with six above-ground shelters and each missile having a thirty-minute launch countdown, but the next squadron’s nine missiles were in three separated groups of three, with individual shelters having a split roof, enabling the missiles to be raised to the vertical in situ, thus saving several minutes of launch time. The next three squadrons had similarly dispersed sites, but this time the missiles were housed in semi-hardened bunkers, recessed into the ground and with even greater separation. The final units were housed in hardened underground silos.
Titan I, which had a range of 10,000 km, was, like the final Atlas, located in silos and raised to the surface for launch; however, it had a new and much faster fuelling system, enabling it to be launched some twenty minutes after the countdown started. There were five Titan I sites, one with eighteen missiles and four with nine each, but the system had only a brief period of service, becoming operational in 1961 and being replaced by Titan II from 1963 onwards, the process being completed in 1966.
Despite its name, Titan II was almost totally different from Titan I, not least because of a 50 per cent increase in range, to 15,000 km. Again, the missiles were sited in squadrons consisting of three widely separated groups of three, with two squadrons at each of three bases, but the new system introduced a completely novel launch system, with the missile being launched from inside the silo. Two other advances in this missile were the use of an inertial guidance system and the use of storable liquid fuel – i.e. the fuel was already loaded in the missile, thus cutting out the time needed to fuel the earlier missiles. In combination these developments resulted in a launch time of just sixty seconds. Fifty-four missiles were deployed, being operational from 1963 to 1987.
By now, the future obviously lay with solid-fuelled missiles, which were safer and more reliable, and in simpler, cheaper and more survivable siting and launch systems. A rail-mobile system was considered for Minuteman I, but the silo option won.
The two-stage Minuteman I was deployed from 1962 onwards in individual unmanned silos, which were scattered over large areas. Ten silos were grouped into a ‘flight’, five flights in a ‘squadron’, and squadrons into ‘wings’; there were four squadrons in each of four wings, while the fifth wing had five squadrons. The overall total was 800 missiles.
Minuteman II was longer and heavier than Minuteman I, with extended range (12,500 km compared to 10,000 km) and a more accurate warhead. It entered service in 1966, and by 1969 it had replaced all Minuteman Is. Of the 450 deployed, ten were subsequently reconfigured to carry the Emergency Rocket Communications System (ERCS) and thus no longer carried nuclear warheads.
Minuteman III introduced a third stage and was also the first US ICBM to carry MIRVs, but its basing and launch systems were the same as those of Minuteman II.
The Missile, Experimental (MX) programme was one of the longest and most controversial in the Cold War, with much of the argument centring on the question of basing. Indeed, MX consumed money at a prodigious rate and gave rise to an industry of its own for many years before it began to make any contribution to Western deterrence. The programme started in the early 1970s, and eventually resulted in the fielding of just fifty Peacekeeper missiles in 1986. After all the argument on different basing systems, these were placed in Minuteman III silos. Peacekeeper had a range of 9,600 km and carried ten W-87 warheads, each with a yield of 300 kT and an accuracy (CEP) of 100 m, giving them an extremely high lethality. During the Cold War these would almost inevitably have been targeted on both Soviet leadership bunkers and ‘superhardened’ ICBM silos.
SOVIET ICBM DEVELOPMENT
The first official rocket-propulsion laboratory in the Soviet Union was opened in 1921, but attention was concentrated on short-range artillery missiles until after the Second World War, when the USSR produced a copy of the German A-4, known under the NATO system as the SS-1, ‘Scud’. The SS-2, ‘Sibling’, was similar, but with Soviet advances to increase range and reliability, while the SS-3, ‘Shyster’, was the first to carry an atomic warhead.
In the 1950s the USSR found itself without a strategic bomber force to counter the B-36s, B-47s and B-52s of the USAF, and the quickest way to produce an answer was an ICBM. The technology of the time was, however, comparatively crude: warheads were heavy, and the sum total of the components, the payload and the fuel needed for intercontinental range came to well over 200 tonnes. Nevertheless, the USSR, which was never deterred by the size of a project, pressed ahead to produce the huge SS-6, ‘Sapwood’, which first flew on 3 August 1957. The necessary thrust was obtained by using a basic missile surrounded by four large strap-on boosters, the main missile and each booster having a 102,00 kgf thrust rocket motor. Thus, the device had a launch weight of no less than 300 tonnes, but was powered by motors with a total thrust of 510,000 kgf.
As a strategic weapon the SS-6 was less than successful: it had a poor reaction time, due to the need to load huge quantities of cryogenic fuel, it was far too big to be put in a silo, its electronics were crude and unreliable, and it was very inaccurate, with a CEP of some 8 km. The knowledge that the USSR had such a powerful launch vehicle had a major psychological impact on the USA, but no more than four SS-6s were ever deployed operationally as ICBMs. The SS-6 was, however, used for space launches for many years, since it could lift the heavy weights needed for programmes such as Sputnik, Luna, Vostok, Voshkod, Mars and Venera.
The first really successful Soviet ICBM was the SS-7, ‘Saddler’, of which 186 were deployed from 1961 until it was withdrawn in 1979 under the terms of SALT I. The SS-7 was the first Soviet missile to enter service using storable liquid fuel. It had two stages giving it a range of some 11,500 km, and was therefore the first Soviet ICBM to pose a realistic threat to the continental USA, although its relative inaccuracy (it had a CEP of 2.8 km) restricted it to counter-value targets.
It was long a feature of Soviet military philosophy that an ambitious programme was backed up by a much less demanding and technically safer system, which in this case was the SS-8, ‘Sasin’. Only twenty-three SS-8s were ever deployed, and they had a limited life from 1965 to 1977.
The SS-9, ‘Scarp’, was the first of the second generation of Soviet ICBMs: a heavy, silo-based missile which became operational in 1966. Numbers peaked at 313 in 1970, remaining at this level until 1975, when retirements began, the last of the type being withdrawn in 1979. Four versions were known: the first to enter service was Mod 1, which had a 20 MT warhead, while Mod 2, the principal production version, had a 25 MT warhead – by far the most powerful warhead ever to achieve operational status in any country. The Mod 3 was a special version which was used to test the Fractional Orbital Bombardment System (FOBS), which was designed to attack the USA from the south-east; it caused considerable concern in the Pentagon. Mod 4 carried three MRVs, which impacted with the same spread as a typical USAF Minuteman missile complex, although it never actually entered service, the mission being allocated to the SS-11 Mod 3 instead.
The SS-10, ‘Scrag’, was the insurance against the failure of the SS-9. This huge missile, which used cryogenic fuels, was shown at the 1968 Red Square parade but never entered service.
The two-stage SS-11, ‘Sego’, used storable liquid propellant and entered service in 1966, eventually serving in three principal variants. Mod 1 had a single 950 kT warhead, Mod 2 had increased range and throw weight, as well as penetration aids and a more accurate warhead, while Mod 3 carried three 200 kT MRVs, the first such system to be fielded by the USSR, with a foot-print virtually identical with that of Minuteman silos. The SS-11 had a long life, with just over half being replaced by the SS-17 and SS-19 in the late 1970s, while the balance of 420 remained until 1987, when they were replaced progressively by the road-mobile SS-25.
Developed concurrently with the SS-11, the SS-13, ‘Savage’, was the first solid-fuel Soviet ICBM, and had an unusual construction with three stages linked by open Warren-girder trusses – a configuration matched only by the earlier SS-10. There were claims in the early 1970s that the SS-13 was being used in a mobile role, but these were never substantiated. The USSR claimed that the SS-25 was a modified version of the SS-13 (which was permitted under SALT II), and flew two missiles in 1986 to demonstrate that this was the case to the USA. Only sixty SS-13s entered service, and the production and maintenance of such a small number must have been very expensive. However, it must be assumed that it played a useful role in the Soviet nuclear force, as the SS-13 remained in service from 1972 until past the end of the Cold War.
The SS-17, ‘Spanker’, which used storable liquid propellant, was developed in parallel with the SS-19 as a replacement for the SS-11 and was in service from 1975 to 1990. It was the first Soviet ICBM to be launched by using a gas generator to blow the missile out of the silo, with ignition taking place only when the missile was well clear. Known as the ‘cold-launch technique’, this method minimized damage to the silo and enabled it to be reused. This caused considerable alarm in the United States, as it was seen to indicate a plan for a nuclear war lasting several days, if not weeks. The second innovation was that several versions carried MIRVs, the first operational Soviet ICBMs to do so: Mods 1 and 3 carried four 200 kT MIRVs, but the Soviets, as always, hedged their bets, and the SS-17 Mod 2 carried a single 3.6 MT warhead
The SS-18, ‘Satan’, the successor to the SS-9, was by far the largest ICBM to be fielded by either of the two superpowers, and its throw weight of 8,800 kg was the greatest of any Cold War missile. Starting in 1975, it was deployed in former SS-9 silos, which were modified and upgraded to take the new missile. Mods 1 and 3 both had a single large 20 MT warhead, while Mods 2 and 4 each had ten 500 kT MIRVs. The SS-18 was described by the USA as ‘extremely accurate’ and ‘designed to attack hard targets, such as US ICBM silos’. Also, according to US sources, the SS-18 force was capable of destroying ‘65–80% of the US ICBM force, using two warheads against each. Even after such an attack, there would still be over 1,000 SS-18 warheads available for further strikes against US targets.’
The SS-19, ‘Stiletto’, was developed in parallel to the SS-17 and entered service in 1971, with a peak deployment of 360; it was the most widely used Soviet ICBM of its generation. It was a hot-launch missile, although it was housed in a canister which reduced silo damage. Various versions of the missile were developed, but the service version was the Mod 3, with six 550 kT MIRVs, each with a CEP of 400 m, which, again according to US sources, meant that ‘while less accurate than the SS-18, [it had] significant capability against all but hardened silos. It could also be used against targets in Eurasia.’ It would therefore appear safe to assume that the SS-19 was targeted against counter-force targets, such as reasonably hardened military targets, but not against ICBM silos, which were the task of the SS-18.
The SS-24, ‘Scalpel’, was fielded in two launch modes, the Mod 1 being rail-mobile, while Mod 2 was silo-based. The actual missiles in each variant were virtually identical, being ten 500 kT MIRVS with a range of 10,000 km and a CEP of 200 m. Mod 1 was deployed in trains with three launchers each, with three rail garrisons, all in Russia; there were four trains each at Kostromo and Krasnoyarsk and three trains at Bershet. Fifty-six of the silo-launched version (Mod 2) were deployed, split between one site in Russia (ten silos) and one site in the Ukraine (forty-six silos).
The SS-25, ‘Sickle’, was the last Soviet ICBM to be fielded during the Cold War. It was a single-warhead missile, carrying one highly accurate 550 kT warhead, and entered service in 1985. At the end of the Cold War 288 missiles were split between nine sites, with further missiles being deployed up to 1994. The missile was road-mobile, but was normally housed in a garage with a sliding roof which could be opened for an emergency launch. Given the necessary warning, however, the fourteen-wheel TELs were deployed to pre-surveyed sites in forests, where they were raised on jacks for stability during launch.
The SS-25 missile was contained in a large cylindrical canister, and the system was reloadable, highly survivable and capable of rapid retargeting. This led US sources to speculate that it was designed for use in a protracted nuclear war as a reserve weapon, when it would ride out the first wave of US attacks on the Soviet nuclear arsenal and then retaliate against surviving targets, which could be selected and set into the warhead at the time. It was during the flight testing of the SS-25 that the Soviets first used encryption on their telemetry down-links, which caused the US to claim that they were acting in contravention of the SALT II agreement.