2
Hard and Deeply Buried Targets

Potential U.S. adversaries worldwide are using intentionally hardened facilities to conceal and protect their leaders, military and industrial personnel, weapons, equipment, and other assets and activities. Such facilities, called hard and deeply buried targets (HDBTs), are a serious challenge to U.S. national security objectives of maintaining the capability to hold such adversary assets at risk. Ranging from hardened, surface bunker complexes to tunnel facilities deep underground, HDBTs are typically large, complex, and well concealed, incorporating strong physical security, modern air defenses, protective siting, multifaceted communications, and other important features that make many of them able to survive attack by conventional weapons. Potential adversaries are increasingly locating HDBTs in basements of multistory buildings located in urban settings, complicating attack planning and increasing the risk of serious collateral effects. This situation places a premium on achieving accurate target characterization so as to obtain the required lethality from precisely delivered weapons during a strike.

Many HDBTs are of a shallow “cut and cover” design, with an equivalent concrete structural overburden of less than 3 meters’ thickness. This type of facility typically has a tactical function, such as providing support for artillery or missile launchers. Many such facilities can be held at risk by current weapons, or weapons under development if deployed, if the numbers of U.S. weapons are adequate, accurate target location coordinates are known, and adversaries’ defenses are overcome. The missile operations tunnels and armament bunkers in some theaters are particularly troublesome because of their sheer numbers, protective berms, and the strategic positioning of their entrances and exits away from direct routes of attack.

Hundreds of much harder facilities (with a concrete overburden equivalent of 20 to 100 meters) protect strategic capabilities (e.g., leadership, command and control, weapons of mass destruction [WMD]) and were built using either conventional drill-and-blast tunneling techniques or more modern mining equipment. These are typically equipped with redundant ventilation, power, and communications systems. U.S. capabilities to place these types of facilities at risk are challenged not only by the depths of burial and redundancies in critical functional systems, but also by sophisticated techniques for camouflage, concealment, and deception, and some collocation of HDBTs in civilian areas. Such facilities, which conceal and protect an adversary’s most valued strategic capabilities, are described in more detail in this chapter.



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Effects of Nuclear Earth-Penetrator and Other Weapons 2 Hard and Deeply Buried Targets Potential U.S. adversaries worldwide are using intentionally hardened facilities to conceal and protect their leaders, military and industrial personnel, weapons, equipment, and other assets and activities. Such facilities, called hard and deeply buried targets (HDBTs), are a serious challenge to U.S. national security objectives of maintaining the capability to hold such adversary assets at risk. Ranging from hardened, surface bunker complexes to tunnel facilities deep underground, HDBTs are typically large, complex, and well concealed, incorporating strong physical security, modern air defenses, protective siting, multifaceted communications, and other important features that make many of them able to survive attack by conventional weapons. Potential adversaries are increasingly locating HDBTs in basements of multistory buildings located in urban settings, complicating attack planning and increasing the risk of serious collateral effects. This situation places a premium on achieving accurate target characterization so as to obtain the required lethality from precisely delivered weapons during a strike. Many HDBTs are of a shallow “cut and cover” design, with an equivalent concrete structural overburden of less than 3 meters’ thickness. This type of facility typically has a tactical function, such as providing support for artillery or missile launchers. Many such facilities can be held at risk by current weapons, or weapons under development if deployed, if the numbers of U.S. weapons are adequate, accurate target location coordinates are known, and adversaries’ defenses are overcome. The missile operations tunnels and armament bunkers in some theaters are particularly troublesome because of their sheer numbers, protective berms, and the strategic positioning of their entrances and exits away from direct routes of attack. Hundreds of much harder facilities (with a concrete overburden equivalent of 20 to 100 meters) protect strategic capabilities (e.g., leadership, command and control, weapons of mass destruction [WMD]) and were built using either conventional drill-and-blast tunneling techniques or more modern mining equipment. These are typically equipped with redundant ventilation, power, and communications systems. U.S. capabilities to place these types of facilities at risk are challenged not only by the depths of burial and redundancies in critical functional systems, but also by sophisticated techniques for camouflage, concealment, and deception, and some collocation of HDBTs in civilian areas. Such facilities, which conceal and protect an adversary’s most valued strategic capabilities, are described in more detail in this chapter.

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Effects of Nuclear Earth-Penetrator and Other Weapons BASIC DEFINITIONS Hard and Deeply Buried Targets The generic term “hard and deeply buried targets” refers to all types of intentionally hardened targets, either aboveground or belowground, that are designed to withstand or minimize the effects of kinetic weapons. Underground Facility The generic term “underground facility” refers to all types of underground hardened structures and facilities regardless of their depth. Hardened Structure The generic term “hardened structure” refers to a structure that is intentionally strengthened to provide protection from the effects of kinetic weapons. All hardened structures can be further grouped into one of three types, defined by the location of the roof of the structure’s functional workspace: Aboveground hardened structure. The roof of the functional workspace is above the ground surface. Included in this category are earth-bermed structures that are not exposed directly to weapons effects and for which air blast effects are reduced owing to the aerodynamic shape of the berm. Shallow underground structure. The roof of the functional workspace is between the ground surface level and 20 meters deep. Deep underground hardened structure. The roof of the functional workspace is covered by 20 or more meters of soil and/or rock. Strategic Hard and Deeply Buried Target The term “strategic hard and deeply buried target” refers to those HDBTs that perform a strategic function, such as command and control of military forces, protection of national leadership, WMD production or storage, and ballistic missile production, storage, or launch. The proposed nuclear earth-penetrator weapon (EPW) is being designed to defeat this target class. BASIC FACTS AND ESTIMATES Following is a concise list of background facts and estimates relating to HDBTs: Potential U.S. adversaries worldwide are using underground facilities to conceal and protect their leadership, military and industrial personnel, weapons, equipment, and other assets and activities. These facilities include hardened surface bunkers and tunnel facilities deep underground. Many underground command, control, and communications (C3) complexes and missile tunnels are between 100 and 400 meters deep, with the majority less than 250 meters deep. A few are as deep as 500 meters or even 700 meters, in competent granite or limestone rock. As identified by the Defense Intelligence Agency, there are about 10,000 HDBTs in the territory of potential U.S. adversaries worldwide.

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Effects of Nuclear Earth-Penetrator and Other Weapons Of the 10,000 HDBTs identified, about 20 percent are estimated to have a major strategic function. Over half of these strategic HDBTs are located near or in urban areas. The number of known strategic HDBTs is increasing at a rate of about 10 percent per year. This increase is attributable mostly to discovery by the U.S. intelligence community and to a lesser extent to construction in countries seeking protection from U.S. military capabilities. With the current U.S. nuclear arsenal, a number of the more important strategic HDBTs cannot be held at risk of physical destruction of the functional area. A few hundred of the strategic HDBTs could be candidates for targeting with the robust nuclear earth penetrator (RNEP) weapon currently under study. EXAMPLES OF STRATEGIC HARD AND DEEPLY BURIED TARGETS Examples of strategic HDBTs are shown in Figure 2.1 and detailed in this section. Representative actual overburdens, not their reinforced concrete equivalents, are described in the following examples. Missile Tunnel Hard Target Type: Deep underground tunnel Function: Deployment area for short-range ballistic missiles (SRBMs) that have a chemical weapon warhead; warhead mating performed in maintenance area Site Location: Remote valley; nearest civilian population center is 30 kilometers away FIGURE 2.1 Examples of strategic hard and deeply buried targets. (See text for details. Acronyms are defined in Appendix D.)

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Effects of Nuclear Earth-Penetrator and Other Weapons Number of Stories or Levels: One Number of Entrances: Two Overburden: 120 meters at working area Geology: Varying layer depths of residual soil, weathered rock, and limestone Berms: Tunnel adits constructed to form a berm Tunnels: Tunnel lining is 1 meter of reinforced concrete from entrance to blast doors, then 0.5 meter reinforced concrete throughout internal cavities Blast Doors: 1 meter of steel-lined reinforced concrete Reinforced Concrete: Compression strength of all concrete is estimated at 4,000 pounds per square inch Deep Underground C3 Complex Hard Target Type: Bunkered facility deep underground Function: Reserve post for providing command, control, and communications support to strategic nuclear forces as well as wartime protection for senior military authorities Site Location: Mountainous region in country’s interior, more than 200 kilometers away from a city of 50,000 and 6 kilometers from a village of 150 Number of Stories or Levels: Multilevel facility connected by elevators, shafts, and tunnels Number of Entrances: Two horizontals entrances and one vertical shaft entrance Overburden: 400 to 700 meters overburden at working area Geology: Single monolithic upthrust of quartzite sandstone Berms: None Tunnels: Tunnel lining reinforced concrete Blast Doors: Sliding double blast doors exist in excess of 0.7 meter thick at each entrance; main entrance is 7 meters wide, and auxiliary entrance is 9 meters wide Reinforced Concrete: Reinforced concrete facing walls installed at both entrances, and a slab of reinforced concrete covering the vertical shaft CW/BW Aboveground Bunker Hard Target Type: Hardened aboveground bunker Function: Chemical weapons (CW) munitions filling (artillery and bombs) and CW munitions storage Site Location: Remote desert area, within a large chemical weapons production and R&D complex; no civilian facilities within a 10 kilometer range; nearest populated area is 40 kilometers northwest of the complex Number of Stories or Levels: One Number of Entrances: One Overburden: 8 meters thick, including two 1 meter burster slabs separated by a 3 meter layer of 8 inch rocks, covered by soil Ceiling: 1 meter of reinforced concrete Walls: 1 meter of reinforced concrete Floor: 2 meters of reinforced concrete Roof: 0.5 meter of steel-lined concrete Blast Doors: 0.5 meter of steel-lined concrete

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Effects of Nuclear Earth-Penetrator and Other Weapons C3I Shallow Underground Bunker Hard Target Type: Shallow underground bunker Function: National-level military command-and-control facility Site Location: Within a large military complex on the outskirts of a large city (population 250,000) Number of Stories or Levels: One Number of Entrances: Four Overburden: Five layers above roof: 3 meters of compacted soil 1 meter of reinforced concrete burster slab 3 meters of crushed/compacted rock 1 meter of reinforced concrete burster slab 3 meters of compacted soil Thickness of: Walls: 1 meter of reinforced concrete Floor: 1 meter of reinforced concrete Roof: 2 meters of reinforced concrete Blast Doors: 0.5 meter of steel-lined concrete C3I Basement Bunker Hard Target Type: Basement bunker Function: National-level command-and-control facility Site Location: Within a military headquarters complex under a six-story Army Headquarters building in a heavily populated (750,000) urban area; civilian structures (hospitals, schools, embassies) all located within a 1 kilometer radius of the facility Number of Stories or Levels: Two-level bunker underneath six-story building Number of Entrances: Two Thickness of: Walls: Exterior, 2 meters; interior, 0.5 to 1 meter of reinforced concrete Floor: 1 meter of reinforced concrete Roof: 4.1 meters of reinforced concrete equivalent above upper bunker level Blast Doors: 4 blast doors, sliding, steel-lined concrete Shallow Accessible Bunker/Silo Hard Target Type: Shallow buried “cut and cover” bunker Function: Biological weapons (BW) agent storage and production Site Location: Collocated within aboveground civilian bioproducts R&D and production complex; hilly terrain, vegetation; large civilian population within a 0.5 kilometer radius of the facility Number of Stories or Levels: One Number of Entrances: One Overburden: 7 meters of compacted soil Walls: 1 meter of reinforced concrete Floor: 1 meter of reinforced concrete Roof: 2 meters of reinforced concrete Blast Doors: 0.5 meter overall; steel-lined concrete