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The Floating Shell Game: Tom Clancy’s 1982 Plan to Fire Nuclear Weapons from a Hovercraft

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U.S. Naval Institute Graphic

U.S. Naval Institute Graphic

The following is from the July, 1982 issue of Proceedings. It was Tom Clancy’s second piece of published work with the U.S. Naval Institute.


A considerable amount of public debate has been held in the past five years on the question of the MX missile system. This weapon would be the most powerful in the U. S. inventory, capable of sending ten thermonuclear warheads to ten separate targets with a high degree of accuracy. It seems fair to observe at the outset that MX is a system with a counterforce capability designed into the package.

The question of the missile’s mission capabilities, however, has been largely ignored in this country. The Stockholm International Peace Research Institute (SIPRI) and other foreign observers have noted that MX is potentially part of a war-fighting, war-winning strategy – something which American officials deny while ascribing this same objective to the Soviets (as might be expected, the Soviet position is a precise mirror-image of our own).

In any case, the debate in this country has centered on the basing system for the missile. It is currently accepted in the defense establishment that many of our Minuteman missiles probably can be destroyed in their silos before the National Command Authority (NCA) can respond to a nuclear attack. Although the preconditions required for a successful first strike are awesome, the problem is one of engineering rather than theory.

Discussions on the MX revolve around how to deploy the missiles in such a way as to assure their survival under the most adverse circumstances. Thus far, the official solution – multiple-protective–shelter (MPS) basing mode-has been rejected. Unfortunately, MPS is not perceived as survivable against a determined attack by Soviet missiles. The Reagan Administration’s recently proposed method of deployment is to have “dense packs” of missiles. This plan also appears to be drawing heavy political fire.

A successful MX deployment system must meet a number of tests:

  • Insensitivity to first strike: The deployment scheme must allow a large proportion of its missiles to survive a strike and retaliate in force. The MX is more likely to deter a war rather than fight one if this criterion is met.
  • Reconstitution of forces: The insensitivity to attack must continue for an indefinite period of time. This will allow NCA to determine how many missiles have survived, choose an appropriate response, and to redirect the missiles to still-valuable targets.
  • Continuous launch capability: The system should be able to launch under the widest range of circumstances, including disablement of the missile carrier itself.
  • Separate vulnerabilities: The distinct nature of this leg of the strategic Triad should be retained, forcing an opponent to contemplate the most difficult range of tasks.
  • Communications security: The most attractive aspect of the land leg of the Triad is the availability of secure two-way communications at all times.
  • Environmental impact: As was demonstrated by the MPS deployment mode; any system which has a negative impact on local populations or environments will generate significant legal and political resistance.
  • Operational safety: Since any deployment system will touch upon civilian areas, its routine operation must not be perceived as a possible danger by the populace.
  • Cost: Ideally, the system should be as inexpensive as possible to initiate, operate, and maintain. To this end, a system that does not operate continuously has long-term advantages.

A number of deployment systems have been examined, and each fails on one or more of these criteria. The MX has been described as “a Rolls Royce without a garage.” But a vehicle exists to deploy the MX that meets the above preconditions: the U. S. Navy’s air cushion landing craft (LCAC).

The LCAC has a standard payload capacity of 60 tons, and an overload capacity of 75 tons. This is less than the weight of the MX (85 tons) , but well in excess of that for any other American strategic system except the obsolete Titan II. The LCAC has a speed of 50 knots, and a range of 200 nautical miles. It can cross land or water, and does minimal damage to the terrain.

Were the MX missiles to be deployed on vehicles of similar performance, they would represent exceptionally elusive targets. Once deployed, the LCAC(M)s would scatter like quail before am incoming strike:

Warning time (minutes) Dispersal area (square miles)

15 638

20 1,134

25 1,772

30 2,552

Indeed, the targeting problem is not unlike that of tracking a moving ship, amplified by the LCAC(M)’s higher speed. Even if we assume in the above case that an adversary knows the exact starting point of each LCAC(M), he would still need to track hundreds of targets in real time-each moving at high speed on a random course. Knowledge of each vehicle’s starting point would require continuous surveillance of a vast terrain, a difficult enough task without the use of even the most elementary countermeasures.

Countermeasures would be used, of course, though they need not be expensive ones. One simple method would be an inexpensive mimic of the MPS mode. For each LCAC(M), we could construct a single, centrally located barn- or hangar-type structure for permanent basing and maintenance, and three or four simpler structures for visual concealment only, disposed radially about 20 miles from the central location.

For the purposes of this discussion, we will deploy MX in the Midwest though the LCAC(M) can probably operate nearly anywhere. The area is wide and flat with a low population density. The LCAC is designed to operate in sea state two, cross ·five-foot vertical obstacles, and climb 13% gradients. In this area, therefore, its cross-country mobility would be largely unrestricted. Adverse environmental conditions – flood, fog, snow, ice – are extraneous to its operation. Attention will have to be paid, however, to possible foreign object damage (FOD) to the turbine engines. But this problem should be readily solvable.

While the rejected MPS basing system promised to be an environmental nightmare, the LCAC(M) would have a negligible environmental impact. At worst, it might flatten a few rows of corn in season (probably not damaging other cereal crops at all), or perhaps awaken hibernating prairie dogs in winter.

The system would not need highly sophisticated navigation gear. While it is important for a missile like MX to know its launch position with great precision, every road junction and farm building could be pre-surveyed to this end – if indeed, this objective has not already been met.

With some additional, creative design work, LCAC(M) could refuel from local civilian sources, making its mobility and endurance in a crisis almost unrestricted.

Let us now address some of the difficulties that such a deployment might encounter:

1. Can a vehicle of sufficient payload capacity and performance be built?

The LCAC prototypes have six turbine engines, two for lifting and four for lateral motion. Production LCACs are expected to have only four engines cross-connected for either purpose. The prototype vehicles are within ten tons of the required payload capacity – not including the weight for erection gear – and already has the necessary physical dimensions to accommodate the missile.

2. Will the altitude of the proposed operational area degrade vehicle performance?

The performance difference might well be noticeable. At the same time, the terrain to be crossed is probably flatter on average than the choppy seas on which the LCAC is designed to operate. As a consequence of this, vehicle performance might actually be enhanced.

3. What additional protection might the missile and its carrier need to survive an attack?

It is worth noting the contrast between the MPS system (with the current Minutemen) and the LCAC(M). While the former compels an adversary to groundburst several thousand warheads, the LCAC(M) is more vulnerable to an airbust. In the former case, groundbursts generate vast clouds of radioactive fallout which are likely to cause severe civilian casualties downwind. With the use of LCAC(M)s, this secondary bonus will not come into play. Moreover, the great mobility of the system under fire probably makes blast protection less important than protection against electromagnetic pulse. This is also an engineering question that is solvable. A few simple computations will demonstrate that hardening the vehicle and missile to withstand peak overpressures of five to nine pounds per square inch will make a successful attack on them virtually impossible.

4. Could NCA communicate with the LCAC(M)s in times of crisis?

Yes. By secure land line and by local VHF/UHF channels, such communications should have a high degree of reliability.

The sensitivity of the LCAC(M) system to a first strike is small. The destruction of all or most of the vehicles would require the real-time tracking of 200 individual targets within an area of at least 500,000 square miles. As noted, hardening of the vehicle to withstand fairly modest overpressures would necessitate a near-quantum jump in Soviet warheads. Even if such an attack were successful, the secondary effects would be much less than a groundburst attack.

After the first strike has been ridden out, the continued ability of the LCAC(M) to survive should be unimpaired. Its indefinite availability for possible action will give NCA the greatest possible flexibility, in selecting and executing a response. The LCAC(M) can launch its missile even when the vehicle is disabled from strike damage or mechanical repair. The LCAC(M) retains the separate nature of the land leg of the Triad; the potential vulnerabilities of this system will be separate and distinct from those pertaining to the other legs.

And the environmental impact of LCAC(M) will be negligible. To limit interference with farming operations conducted in the deployment area, ordinary shelter-to-shelter shuttling could be limited to rights-of-way – not more than 100 feet wide – which could be leased for nominal charges, where certain cash crops could probably be grown without difficulty.

The safety of hovercraft is self-evident. A complete power failure during transit would cause no more than the vehicle’s coming to rest.

Deployment of the LCAC(M) would involve the modification of an existing item of military hardware on which research and development have already been completed – a low technological risk. It will not require the construction of numerous and costly hardened sites. Moreover, it need not be operated continuously; although readiness for emergency dispersal will be necessary at all times, ordinary shuttling from one place of concealment to another need not be frequent. Its manning requirements should be relatively modest. The LCAC(M) should, therefore, have lower procurement and operating costs than any other acceptable deployment mode.

It would appear that LCAC(M) meets all of the criteria for a successful MX deployment system. It goes on to provide some additional bonuses which could be decisively important.

First, the system is verifiable. Since its security is based on mobility and not directly on concealment, knowledge of the day-to-day location of the missiles cannot compromise their safety. Their actual numbers, therefore, will never be in doubt. This could enhance efforts to reach an international arms agreement.

Second, the system leaves room for expansion. Should it become desirable to retire Minuteman, and replace it with a “common” missile like the Trident II, the existing LCAC could readily accommodate it. This would convert the entire land leg of the Triad to full mobility, and quite possibly could remove the counterforce strike from the range of options available to an adversary.

Third, because this system adopts existing hardware, it is likely that it could be deployed more rapidly than any other acceptable alternative.

Fourth, a land vehicle with the LCAC’s operating characteristics has numerous potential uses· in a civil emergency. While it may not always be desirable to lose the services of a missile launcher even temporarily, military equipment has a long and honorable history of serving the citizenry when needed. The realization by civilians that LCAC(M)s might be available for rescue ·and other missions when needed may turn it into a potential community asset rather than liability. The peaceful use of LCAC(M) would make it unique among our strategic assets.

The LCAC could also be easily adapted by the Air Force as a solution to a thorny problem. Its operational characteristics have sufficient attraction to merit a detailed engineering analysis of its practicality and cost. As a means of simplifying our own strategic posture, it would, at the same time enormously complicate the tasks of a potential adversary, making it affordable and effective deterrent.

Author’s Note: I wish to express my appreciation to Major H. W. Peterson, U.S. Marine Corps; Lieutenant Colonel Neal Mitchell, U.S. Marine Corps; and Lieutenant Commander R. E. Chatham, U.S. Navy; they were most helpful in the preparation of this article.