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.*
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.
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 footprint 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.’1
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.’2 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.
The original German A-4 missile employed a brilliantly simple road-mobile system, in which the missile was carried on a four-wheeled trailer known as a Meillerwagen. When the missile was to be launched, the Meillerwagen raised it to the vertical and then lowered it on to a small launch platform. Each site had a crew of 136 men, with many more men and vehicles in the logistics chain.
The Germans also gave active consideration to launching the A-4 missile from a train. According to a 1944 plan, each train would carry six ready-to-use missiles, and include an erector–launcher car, seven fuel-tanker cars, a generator car, a workshop, a spares car and several cars for the crew. On top of this, however, the train would also carry all the vehicles normally associated with a missile battery, in order that the unit could dismount from the train and operate independently of it, which brought the whole battery up to the unwieldy total of seventy to eighty freight cars, probably requiring at least two separate trains. Separate logistic trains were planned to bring further supplies of fuel and missiles. Prototype trains were running before the end of the war, but the system was not a practicable proposition in view of the air supremacy of the Allies, for whom all trains were a high-priority target.3
ICBM forces were originally built to threaten the opponent’s civil population, which in itself was not a difficult task: the warheads were relatively inaccurate, but the cities were large and the warheads powerful. It was obviously highly desirable, from both political and military viewpoints, to defend the population from this threat, in the same way that bombers had been opposed by a mixture of fighters and anti-aircraft guns during the recent war. It was not feasible at the time to intercept incoming ICBMs, so the only defence was to attack the ICBMs at their source, which could be done only by conducting a pre-emptive strike with other ICBMs. Thus the position was rapidly reached where the ICBMs’ principal target was the other side’s ICBMs, moving on to other missions only when that first battle had been decided. It was therefore necessary to optimize the attacking potential of one’s own missiles while ensuring their survivability in the face of an opponent’s first strike. There were four possibilities:
• superhardened silos, which would withstand even the most powerful incoming warhead;
• using a greater number of silos than missiles, so that the opponent would waste warheads on empty silos;
• making the missiles mobile, as the Germans did, so that the enemy could not locate them;
• using anti-ballistic-missile (ABM) defences.
The essence of the problem can be illustrated by a simplified example in which the aggressor (A) has 100 ICBMs, each with ten warheads, while the other side (B) has 500 ICBMs, each with three warheads. (For the purpose of this example, all missiles and warheads are perfectly available and reliable, and each warhead will kill one silo.) Thus A is capable of destroying 1,000 silos, and if he carries out a pre-emptive strike he requires to use only fifty missiles, leaving B with no missiles. A still has fifty missiles and is clearly the winner. If, however, B builds another 500 silos, but no more missiles, and spreads his 500 ICBMs randomly among the 1,000 silos, A, not knowing which silos are occupied, must attack all 1,000. Both sides then end up with zero ICBMs, which is a better outcome for B than the first, but is unsatisfactory from a military point of view. But if B now builds a total of 2,000 silos, half his missiles (i.e. 250) must survive the attack.
The first missiles, such as the early Atlas and Thor, were located in a shed, primarily for protection from the weather, and were taken out to enable them to be raised to the vertical for fuelling and launch. The missiles were also located close to each other. Both factors together made the missiles extremely vulnerable to incoming missiles, which did not need to be too accurate to achieve a kill.*
The next step was to place the missiles in semi-hardened shelters and to separate these shelters so that one incoming warhead could not destroy more than one missile. In addition, the shelters had split roofs, so that the missile could be raised, fuelled and launched without wasting time moving it out on to a launch pad. As the perception of the threat increased, the spacing between individual missiles increased yet further and the shelters became bunkers, recessed into the ground.
The next step was to mount the missile vertically rather than horizontally, and to put it in a hole in the ground. The USAF, however, adopted a ‘halfway’ system with the Atlas and Titan I missiles, in which the missile stood upright in a silo which, in the case of Atlas, was some 53 m deep and 16 m in diameter, resting on the launch platform, which was counterbalanced by a 150 tonne weight. The launch procedure involved fuelling the missile in the silo and then using hydraulic rams to raise the entire launch platform and missile to the surface, where the missile was then launched. Titan I had a super-fast fuelling system and a high-speed elevator which reduced reaction time to approximately twenty minutes, while the silo and all associated facilities were hardened to withstand an overpressure of 20 kgf/cm2.
A completely new launch system was introduced with Titan II, in which the missile was launched direct from the silo. There was, however, considerable concern about the effects of the rocket efflux on the missile during the few seconds that the missile was still inside the silo, so the missile rested on a large flame deflector, which directed the efflux into two large ducts exhausting to the atmosphere a short distance from the silo. Each missile complex was 45 m deep and 17 m wide and occupied nine levels, which housed electrical power, air conditioning, ventilation, and environmental protection, as well as hazard sensors and the associated corrective devices. At the centre was the launch duct, in which the missile was suspended in an environmentally controlled atmosphere. A walkway extended from the missile silo to a blast lock which provided controlled access between the silo and the tunnels leading upward to the above-ground access and laterally to the launch-control centre (LCC). The LCC was a three-level, shock-isolated cage suspended from a reinforced-concrete dome and housed two officers and two enlisted men. As with the Titan I silo, the Titan II silo was hardened to 20 kgf/cm2.
When it learned that the Soviets were launching direct from the silo, the USAF followed suit and the Minuteman I missile became the first US missile to use the ‘hot launch’, in which the missile rose from the silo surrounded by the flames and smoke from the rocket motor. The next Soviet innovation was the ‘cold launch’, in which a gas generator within the silo produced a pressure sufficient to propel the missile some 20–30 m clear of the silo before its first-stage motor fired. This protected the silo from damage, enabling it to be reused within a fairly short space of time. It was used by the Soviets from the SS-17 onwards, and by the USAF in Peacekeeper (MX).
Following their introduction in the mid-1960s, underground silos became increasingly complicated and expensive structures. Ideally they were located at a relatively high altitude, to improve the missiles’ range, and in springy ground, to absorb as much as possible of the shock waves from incoming warheads. The silo was a vertical, steel/reinforced-concrete tube, housing an elaborate suspension and shock-isolation system which supported the missile as well as providing further insulation to minimize the transfer of shock motion from the walls and floor of the silo to the missile. The top third of the silo housed maintenance and launch facilities, which were known as the ‘head works’ in USAF parlance. Finally, the missile tube was capped by a massive sliding door, which provided protection against overpressure by transmitting the shock caused by the explosion of an incoming warhead to the cover supports rather than to the vertical tube containing the missile; it also provided protection against radiation and EMP effects. The door was designed to sweep the area as it opened, to prevent debris falling into the silo tube and possibly interfering with the launch process.
Individual silos were grouped together for control purposes, but were sited sufficiently far apart to ensure that one incoming warhead could not destroy more than one missile. Control was exercised by an underground command centre, manned by a small crew of watchkeepers, whose functions included operating the dual-key safety system in which launch could be authorized only by two officers acting independently. This command centre was linked to its superior headquarters and to the individual silos under its control by telecommunications and by systems-monitoring links. This introduced a further problem: the vulnerability of these links to blast and, in particular, to electromagnetic pulses (EMP). Making these links survivable against the perceived threats (known as ‘nuclear hardening’) became an increasingly complex and expensive undertaking as the Cold War progressed.
The protection factor (‘hardness’) of a silo was measured by its ability to withstand the overpressure resulting from the blast effects of a nuclear explosion, and was expressed in kilograms-force per square centimetre (kgf/cm2) or pounds per square inch (psi) (1 kgf/cm2≈14.2 psi). In the USA, the Atlas, Titan I and Titan II silos were constructed with a hardness of 20 kgf/cm2 (300 psi), while the Minuteman I silos (mid-1960s) were built with a hardness of some 85 kgf/cm2 (1,200 psi). Finally, in the 1970s, Minuteman III/Peacekeeper silos were built with a hardness of 140 kgf/cm2 (2,000 psi). By this time, however, the silos were so expensive that, despite reports that the Soviets were ‘superhardening’ their silos to resist overpressures of 425 kgf/cm2 (6,000 psi), Congress repeatedly refused to authorize any further hardening of US silos.
The Soviet programme of silo building, refurbishment and hardening was more successful. The earliest silos, built before 1969, were hardened to withstand an overpressure of some 7 kgf/cm2 (100 psi), with the next generation built to 20 kgf/cm2 (300 psi). Those built in the early 1970s for the SS-18 could withstand 425 kgf/cm2 (6,000 psi), which was achieved using concrete reinforced by concentric steel rings.
Although most of their ICBMs were always sited in silos, both the USA and the USSR repeatedly examined alternatives, both to increase survivability and, perhaps of greater importance in the USA than in the USSR, to reduce costs. In the USA, environmental factors also became an increasingly important consideration.
One of the US schemes was called Multiple Protective Structures (MPS) and consisted of a number of ‘racetracks’, each about 45 km in circumference and equipped with twenty-three hardened shelters. One mobile ICBM, mounted on a large wheeled TEL, would have moved around each racetrack at night in a random fashion, with decoy TELs and missiles adding to the adversary’s uncertainties. Basic MPS involved 200 missiles moving between 4,600 shelters covering an area of some 12,800 km2, but a more grandiose version envisaged 300 missiles moving around 8,500 shelters.*
An enhanced version of MPS was proposed in the early 1980s, in which a new Small ICBM (SICBM) would have been deployed in fixed, hardened silos distributed randomly among the 200 racetracks of the MPS system, thus adding to the aiming points for the Soviet ICBM force. It was intended that the SICBM would be 11.6 m long and weigh 9,980 kg, have a range of 12,000 km, and carry a single 500 kT warhead; it would have been launched by an airborne launch-control centre. SICBM would have been housed in a tight-fitting container placed in a vertical silo hardened to approximately 530 kgf/cm2, and it would have required an exceptionally accurate incoming warhead to destroy such a target. Various other launch methods were also considered for SICBM, including a road vehicle, normal silos, airborne launch from a transport aircraft, and (possibly the only time this was ever considered for an ICBM) from a helicopter.
Another scheme was based on the racetrack principle of MPS, but this time with the TELs running inside shallow tunnels, 4 m in diameter. The TELs would simply have kept moving, thus avoiding the need for shelters, and would have had large plugs fore and aft to protect against nuclear blast within the tunnel. If required to launch, the TEL would have halted and used hydraulic jacks to drive the armoured roof upwards, breaking through the surface until the missile was raised to the vertical.
Deep Basing (DB) involved placing the ICBMs either singly or in groups deep underground, where they would ride out an attack and then emerge to carry out a retaliatory strike. One of the major DB schemes was the ‘mesa concept’, in which the missiles, crews and equipment were to be placed in interconnecting tunnels some 760–915 m deep under a mesa or similar geological formation.* Following an enemy nuclear strike, the crews would have used special machines to dig a tunnel to the surface and then brought the launcher to the open to initiate a retaliatory strike. This scheme’s disadvantage lay in its poor reaction time and the difficulty it posed for arms-control verification. From the practical point of view it would have been necessary to find rock which was both fault-free and sufficiently strong to resist a Soviet nuclear attack, but which could nevertheless be drilled through in an acceptable time and without the machinery becoming jammed by debris. On top of all that, a second incoming nuclear strike when the drilling machine was near to the surface would have caused irreparable damage. A related project (Project Brimstone) examined existing deep mines, but also proved unworkable.
A totally different approach, known as Closely Based Spacing or ‘Dense Pack’, was also considered. This suggested that, instead of spacing missile silos sufficiently far apart to ensure that not more than one could be destroyed by one incoming warhead, 100 MX missiles should be sited in superhardened silos placed deliberately close together. The idea was that this would take advantage of the ‘fratricide’ effect in which incoming warheads would be deflected or destroyed by the nuclear explosions of the previous warheads. A spacing of the order of 550 m was suggested, and it was claimed that in such a scheme between 50 and 70 per cent of the ICBMs would have survived.
All the basing methods discussed above were either static or involved limited movement in a closed circuit, but the question of mobile basing was often considered as well. As described earlier, the German A-4 was designed as a road-mobile system, but an alternative rail-based option was also considered, and a similar scheme was designed and tested during the development phase of the Minuteman I. The plan was to have fifty trains, each of some fourteen vehicles, which would have included up to five TEL cars, each carrying a single missile, together with command-and-control, living-accommodation, and power facilities. The scheme was examined in great detail, and a prototype ‘Mobile Minuteman’ train was tested on the public railway. Although the scheme proved feasible, it was dropped in favour of silo deployment.
A similar proposal was considered during the long development of the Peacekeeper (MX) system, and very nearly became operational. This version would have consisted of twenty-five missile trains, each carrying two missiles. Each train would have consisted of the locomotive and six cars: two missile launch cars; a launch-control car, a maintenance car, and two security cars. In peacetime the trains would have been located in a ‘rail garrison’ sited on an existing Strategic Air Command base, which would have contained four or five shelters (known as ‘igloos’), each housing one train. These garrisons would each have covered an area of some 18–20 hectares, with tracks leading to the USA’s 240,000 km national rail network. On receipt of strategic warning the trains would have deployed on to this national network, where they would have rapidly attained a high degree of survivability. This scheme was under active development from 1989 until its cancellation in 1991.
As we have seen, the Soviet SS-24 Mod 1 was actually fielded in the rail-mobile mode. There were three rail garrisons, all in Russia, with four trains at two sites and three trains at the third. The trains had one launcher each, with two further cars for launch control, maintenance, and power supply.
The Soviets also fielded a road-mobile ICBM, the SS-25, which was also the last Soviet ICBM to enter service during the Cold War. This single-warhead missile was carried on a fourteen-wheeled TEL, which was raised on jacks for stability during the launch. The TEL and its missile were normally housed in a garage with a sliding roof which would be opened for an emergency launch. Given the necessary warning, however, the TELs deployed to pre-surveyed sites in forests.
One US proposal was the ‘continuous patrol aircraft’, in which a packaged missile was carried inside a large, fuel-efficient aircraft. On receipt of verified launch instructions, the missile would have been extracted by a drogue parachute, and once it was descending vertically its engine would have fired automatically, enabling the missile to climb away on a normal trajectory. Tests were carried out using a Minuteman I missile transported by a C-5 Galaxy and were completely successful. Large numbers of aircraft would have been needed to maintain the number required on simultaneous patrol. It would have been very difficult for a potential enemy to track them and even more difficult to guarantee the destruction of every airborne aircraft in a pre-emptive strike, but the main weaknesses of the scheme were the vulnerability of the airfields, the enormous operating costs, and, to a lesser degree, the decreased accuracy of the missile.
* A cruise missile flies within the earth’s atmosphere, using aerodynamic lift to overcome gravity and an engine/motor to overcome drag. It is essentially an aircraft with some form of guidance system to replace a human pilot.
* The specifications of German and US land-based strategic missiles are given in Appendix 7.
* ERCS involved placing a communications package on the missile in place of the warhead. The missiles could then be launched to provide communications relay facilities between national command posts and nuclear forces in the event that all other means of communication had been lost.
† The specifications of Soviet land-based strategic missiles are given in Appendix 8.
‡ This missile served in the Red Army for many years, and developed versions are still in wide-scale use in the 1990s in Middle Eastern and Asian armies.
* Cryogenic fuels are liquified gases which need to be kept at low temperatures and are therefore difficult to handle.
* This explains the brevity of Thor’s operational life with the UK air force.
* It was estimated that among the requirements of the racetrack scheme would be: cement – 600,00 tonnes; sand – up to 48 million tonnes; liquid asphalt – 954 million litres; petroleum fuels – 568 million litres; water – 81.3 billion litres. In addition, thirty-five federal laws would have impacted on the land-acquisition process, and the scheme would have required the fourth largest city in Nevada to be built from scratch and then maintained.4
* A mesa is a type of high, rocky tableland with precipitous sides, found in certain parts of the USA.