DF-41 - Multiple Shelters
American researchers using commercial satellite imagery reported in June, July and August 2021 that China appeared to be significantly expanding the number of launch silos for its arsenal of intercontinental range ballistic missiles. China may be mirroring the approach called the “shell game” designed by the United States in the late 1970s for basing some of its missiles.
Using images provided by the satellite imaging company Planet, Jeffery Lewis and Decker Eveleth from the James Martin Center for Nonproliferation Studies (CNS) at the Middlebury Institute of International Studies at Monterey (California) found that China is building 119 silos in the desert of the northwestern province of Gansu. The 119 new silos are spread across approximately 1,800 square kilometers near Yumen, a city in Gansu province, with each spaced approximately 3 kilometers apart. Images show that construction began in March 2020, but most building was done since February 2021.
Then Matt Korda and Hans Kristensen on 26 July 2021 that further satellite images revealed that China was building a second nuclear missile silo field. "The Hami missile silo field is in a much earlier stage of development than the Yumen site. Construction began at the start of March 2021 in the southeastern corner of the complex and continues at a rapid pace. Since then, dome shelters have been erected over at least 14 silos and soil cleared in preparation for construction of another 19 silos. The grid-like outline of the entire complex indicates that it may eventually include approximately 110 silos."
And on 12 August 2021 Rod Lee, China Aerospace Studies Institute, reported that "By mid-May 2021, the People’s Liberation Army (PLA) likely began construction of a potential intercontinental ballistic missile (ICBM) silo site in Hanggin Banner, Ordos City, Inner Mongolia (approximately at 40.113, 108.104). Images taken by the European Space Agency’s Sentinel-2 mission between 16 May and 9 August 2021 reveal a construction footprint similar to those found at known PLA ICBM silo construction sites at Jilantai, Guazhou (typically referred to as the Yumen site), and Hami."
The multiple protective shelter (MPS) concept seeks to maintain the capabilities of a fixed land-based ICBM force, while protecting the force from attack, by hiding the missiles among a much larger number of missile shelters. If the attacker does not know which shelters contain the missiles, all the shelters must be attacked to ensure the destruction of the entire missile force. Thus, the logic of MPS is to build more shelters than the enemy can successfully attack, or at least to make such an attack unattractive by requiring the attacker to devote a large number of weapons to attack a relatively smalIer force. The technical and operational requirements of hiding the missiIes among the shelters, formally known as preservation of location uncertainty (PLU) wouId be a new task for missile land basing, and was one of the more challenging aspects of MPS.
Inherent in the strategy of MPS is that the number of shelters constructed be keyed to the size of the threat. Growth in the number of accurate warheads wouId require a larger deployment of missile shelters to maintain the same expected survival rate for missiles.
In the United States, the Air Force’s baseline MX Peacekeeper system had been in full-scale engineering development since September 1979, and was modified in the spring of 1980 to include a horizontaI loading dock configuration for the missile shelter. As proposed, the baseline system consisted of 200 MX missiles among 4,600 concrete shelters, with each m issile deployed in a closed cluster of 23 shelters. These shelters would be spaced about 1 mile apart and arranged in a linear grid pattern. Each shelter would resemble a garage, or loading dock, into which a missile could be inserted horizontally.
Missile location uncertainty would rely on the use of specially designed missile decoys of similar, though not identical, physical characteristics to the real missile, and the employment of operational procedures that would treat missile and decoy alike. Large transport trucks could shuffle missiles and decoys among the shelters in order to keep the precise location of the missiles unknown to outside observers.
An alternative to employing horizontal shelters for MPS is to house the missiles in more conventional vertical shelters. The total construction costs of 4,600 vertical and horizontal shelters were $5.1 billion and $6.3 billion respectively (in fiscal year 1980 dollars), a difference of $1.2 billion. The transporter required for the vertical mode could be smaller than for the horizontal shelter.
Aside from the difference between whether the missile is stored horizontally and erected to vertical for launch, or stored vertically in a ready launch position, there are several important issues. One issue, and perhaps the primary one, is shelter hardness. Pound for pound of concrete, vertical shelters are more resistant (harder) to the effects of nearby nuclear detonations. Shelter response is easier to analyze and we have more experience in testing and building vertical shelters. A second important issue is the ease and speed of missile movement, particularly the insertion and removal times of the missile at the shelter. A horizontal shelter allows a simple roll transfer of the cargo between the transporter and the shelter; transfer for a vertical shelter requires the additional transporter operation of erecting the missile to vertical for insertion and removal from the shelter.
Inherent in the strategy of MPS is that all shelters appear to the attacker as equally IikeIy to contain a missile This assumption is important, since if the attacker were to find out the location of alI the missiIes, it wouId defeat the design of the system. The task of maintaining a PLU-perfect system — of keeping the missile location secret — was essential to successful MPS deployment. With increased study of this issue in the early 1980s, the defense community came to realize the magnitude of the PLU task. What made PLU so challenging is that it is a many faceted problem, dealing with a variety of missile details Moreover, PLU must be made an integral part of the design process at every level. Furthermore, the present expectation is that the design process for PLU will be ongoing throughout deployment, with continuous efforts at enforcing and improving missile location uncertainty through improved PLU countermeasures and operations.
To accomplish this task of missile concealment, it is necessary to eliminate all indications, or signatures, that could give away the location of the missile One such set is the set of alI physical signatures of the missiIe and associated missile equipment. This set includes weight, center of gravity, magnetic field, and many others By utilizing these physical signatures, missile location might be inferred by making measurements outside the shelter or missile transporter, looking for those signatures that could distinguish location of the missile. Such signatures span the spectrum of physical phenomena, many with a range of detectability of hundreds of miles, if not adequately countermeasure.
The physical signatures of the missile run into the scores, with the magnitude and range of each dependent on design detaiIs and material construction of the missile, shelter, and transporter. Against each of these signatures that might compromise missile location it is considered desirable to design and install a set of specific countermeasures. These countermeasures include simulating missile signatures with decoys, masking or reducing the magnitude and range of the signatures, and confusing an outside observer by engineering a set of signatures that vary randomly from decoy to decoy in order to make it more difficult to determine which shelters contain the missiles.
A second set of missile signatures to be eliminated are operational signatures The task here is to eliminate all operating procedures that could distinguish the missile and thereby betray its location. Otherwise, missile placement might be inferred by observing personnel operations.
In addition to physical missile signatures, it is necessary that routine procedures of missile transport and maintenance do not expose the location of the missile, This consideration means that when carrying out missile-related and mass-simulator-related operations, personnel must do the same things, in the same time interval, with the same equipment at all sites. For example, when it becomes necessary to return the missile from maintenance to the shelter, the transporter must visit all of the shelters and either deposit or simulate deposit of the missile. If the operator knows in which shelter he is depositing the missile, care must be taken that any actions on his part, such as outward behavior or conversation with colleagues, do not give clues to missile location.
Internal information is a third set of signatures. This set includes the piecing together of many observations to arrive at a pattern recognition of data from which one can infer missile location. Confidence cannot be obtained until full-scale field tests have been done, when missile signatures can be more retiably identified and analyzed.
It may not be possible to be certain that PLU has not been broken; a break (or even a small fracture) of PLU may likely be a silent event. For all the scores of signatures that have been successfulIy countermeasure, it takes only one accessible uncountermeasured signature to imperil the survivability of the entire missile force. On the other hand, it is reasonable to expect that personnel running a vigorous program to monitor PLU in operation will be more aware of compromises in the system than an outside agent wouId Iikely be.
Since the idea of MPS is not to build a shelter that can survive a direct hit, but one that can survive the effect of direct hits on its neighboring shelters, the requirements for shelter hardness are much less than for the typical ICBM silo. The harder the shelter is made, the closer the shelters can be spaced and still withstand the effects of nearby nuclear detonations. Conversely, the farther apart the shelters are spaced, the less hard the shelters need be made.
Because the number of nuclear detonations in such an attack would run into the many thousands of megatons, there is concern that civilian deaths resulting from radiation fallout would be so large that it might be questionable if such an attack could in any sense be considered a “limited counterforce” strike.
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