The fundamental role of U.S. nuclear weapons, which will continue as long as they exist, is to deter nuclear attack on the United States, its allies, and its partners. To do this, U.S. nuclear weapons must remain ready for use, and the United States must plan for this eventuality in the hopes that it will never come to pass. Therefore, the United States engages in activities to ensure the continued readiness of required quantities of nuclear weapons and delivery vehicles, and the United States also develops nuclear weapon targeting plans. This chapter will provide an overview of the various types and quantities of weapons in the U.S. nuclear stockpile, their functional categorization, the logistics and planning associated with their maintenance and delivery systems, and issues associated with their employment and targeting strategies.3.2 Warhead Types
All nuclear weapons in the U.S. stockpile are designated either as a warhead or as a bomb. In this handbook, the term “warhead” denotes individual weapons without distinguishing between “W” or “B” designators, and the terms “weapon” and “warhead” are used interchangeably. Additionally, the term warhead-type is used to denote a population of weapons with the same design. For a complete list of all weapons-types in the stockpile since 1945, see Figure 3.1.
Throughout the history of nuclear weapons development, the United States has developed families of warheads based on a single warhead design. Thus, some weapons in the U.S. stockpile were developed as modifications to an already-complete design. For example, the B61 bomb has had 11 variations over time. Each variation was designated as a different modification, or Mod. Each Mod used the basic design of the B61, but each Mod had a few different components that changed the operational characteristics of the weapon in a significant way. Five of these Mods are still in the current stockpile: B61-3, B61-4, B61-7, B61-10, and B61-11. The use of this system of modifications provides significant cost savings because, in this model, proven and tested designs are modified rather than beginning each next generation warhead with a completely new weapon design. This approach also provides a more efficient way to conduct quality assurance testing and evaluation because warhead Mods that have a very large percentage of common components can be tested as a family of warheads.
All nuclear weapons in the U.S. stockpile are designated as strategic or non-strategic. Strategic weapons are those delivered by intercontinental ballistic missiles (ICBMs), submarine-launched ballistic missiles (SLBMs), or heavy bombers. These are the three “legs” of the U.S. strategic nuclear force, commonly referred to as the “nuclear triad.” The United States maintains nuclear weapons that rely on all three of these delivery systems.
All other nuclear weapons are non-strategic. Non-strategic nuclear weapons (which are sometimes called “tactical” nuclear weapons) may include: bombs delivered by non-strategic aircraft—usually dual-capable aircraft (DCA) that can be used for both nuclear and conventional missions; warheads in cruise missiles delivered by non-strategic aircraft; warheads on sea-launched cruise missiles (SLCM); warheads on ground-launched cruise missiles (GLCM); warheads on ground-launched ballistic missiles (GLBM) with a maximum range that does not exceed 5,500 kilometers, including air-defense missiles; warheads fired from cannon artillery; atomic demolition munitions (ADM); and anti-submarine warfare nuclear depth bombs (NDB). Figure 3.2 shows U.S. nuclear forces by categories during the Cold War and in the present day.
As stated in the 2010 Nuclear Posture Review Report, the United States is committed to reducing the role and number of its nuclear weapons. Nuclear weapons stockpile reductions are commensurate with the sustainment of an effective nuclear force that provides continued deterrence and remains responsive to new uncertainties in the international security arena, as long as nuclear weapons exist.
Nuclear weapon stockpile quantities are authorized by Presidential Directive annually. The directive includes specific guidance to the Department of Defense (DoD) and the Department of Energy (DOE) (to be carried out through the National Nuclear Security Administration (NNSA)); it also includes a Nuclear Weapons Stockpile Plan (NWSP) that authorizes specific quantities of warheads, by type, by year, for a multi-year period.
From World War II through 1967, the U.S. stockpile quantities for both strategic and non-strategic warheads increased. By the end of 1967, both the former Soviet Union and the United States each had more than 30,000 warheads, and the majority of each stockpile consisted of short-range, non-strategic warheads. For the United States, the large number of stockpiled non-strategic warheads offset the vast advantage that the former Soviet Union had in conventional military forces. Beginning in 1968, the United States began a significant reduction in non-strategic warheads, while continuing to increase its quantities of strategic warheads. This began a shift in priority away from non-strategic nuclear weapons.
In 1991, the United States signed the first Strategic Arms Reduction Treaty (START I). At that time the total U.S. stockpile was approximately 19,000 nuclear weapons, of which more than half were non-strategic warheads (and thus unaffected by the treaty). Also in 1991, President George H.W. Bush initiated drastic reductions in non-strategic nuclear weapons. In the Presidential Nuclear Initiative (PNI) of 1991, the president announced that the United States would retain only a small fraction of the Cold War levels of non-strategic nuclear weapons. The PNI decision significantly reduced the number of U.S. forward-deployed nuclear weapons in Europe and eliminated all non-strategic systems, with the exception of gravity bombs (retained primarily to support the North Atlantic Treaty Organization (NATO) in Europe) and the Tomahawk SLCM, which was removed from deployment but retained as a hedge. Figure 3.3 shows the relative quantities of strategic and non-strategic warheads over time.
The START I treaty put the United States on a path to a total stockpile of approximately 10,000 warheads, of which the majority were strategic weapons. As a result of the 2004 Strategic Capabilities Assessment, the United States reduced its total nuclear weapons stockpile to approximately 5,113 total warheads in 2009. Figure 3.4 shows the size of the U.S. nuclear stockpile from 1945 to 2009.
The New START will lead to further reductions in the total number of U.S. nuclear weapons. As of September 30, 2009, the U.S. stockpile of nuclear weapons consisted of 5,113 warheads. This represents an 84 percent reduction from the stockpile’s maximum (31,255) at the end of fiscal year 1967, and over a 75 percent reduction from its level (22,217) when the Berlin Wall fell in late 1989. Figure 3.5 provides total U.S. stockpile quantities from 1962 to 2009. Figure 3.6 shows the total number of warhead dismantlements from 1994 to 2009.3.4 Stockpile Composition
The current U.S. stockpile composition is determined by a number of factors but is most strongly influenced by the fact that the United States has produced no new nuclear weapons since 1991. The stockpile is composed of weapons developed and produced during the Cold War and maintained well beyond their original programmed lives for roles and missions that have evolved significantly since their original production. A large part of modern stockpile management (since the end of the Cold War) involves maintaining aging weapons in an environment where they cannot be replaced once they are dismantled or irreparable. Thus, stockpile composition refers not only to the differences among bombs and warheads and strategic and non-strategic weapons, but also to the various stockpile categories into which the weapons are divided for the purpose of being able to maintain the required numbers of operationally deployed weapons (those which could be deployed if they were ever needed).
As part of stockpile composition management, it is necessary to identify the numbers, types, and configurations of nuclear warheads required to support an array of employment options and address a range of possible contingencies. The United States must maintain the required number of operationally ready weapons to ensure confidence in the credibility of the nuclear deterrent, maintain strategic stability with Russia, and assure allies and partners of the reality of the U.S. nuclear umbrella. Because some contingencies are based on strategic warning—meaning that the United States would know in advance that it might need to employ its nuclear weapons to respond to emerging circumstances—not all nuclear weapons must be maintained in an operationally ready mode. To save money and to account for limited facilities and capabilities, some weapons are maintained in less-ready modes requiring maintenance action or component replacement/production to become operationally ready. Other warheads are maintained in such a way that they can serve to fill in behind weapons that need repair or are being surveilled.
Because all U.S. nuclear weapons are not ready for immediate use all of the time, balancing the various operational requirements against logistical and fiscal realities is often a difficult task. Because, at this time (and for many years into the future), the United States has no capability to mass produce fissile components for nuclear weapons, U.S. stockpile composition must be managed to provide a hedge in the event of a technological failure or to augment U.S. nuclear forces in response to geopolitical reversals. Stockpile composition is a function of configuration management, or the categorization of warheads by function and readiness state, and the associated logistical planning.
Because the United States cannot devote unlimited resources to the maintenance of the stockpile, choices need to be made regarding the configuration of its stockpile through a process known as configuration management.
Stockpile maintenance is an intricate process that ultimately involves almost every part of the NNSA Nuclear Security Enterprise and organizations with nuclear missions within the DoD. This joint DoD-NNSA process coordinates technical complexities and operational needs associated with the various weapons systems. The Project Officers Groups are at one end of this joint process while the NWC is at the other. (For an explanation of the role of the NWC and the POG in the stockpile management process, see Chapter 2: Stockpile Management, Processes, and Organizations.)
Based on employment plans, hedge requirements, and logistical requirements, the U.S. stockpile plan specifies the number of warheads required to be operational (which requires funding to keep limited life components (LLCs) functioning) and the number of warheads that can serve an essential purpose in a non-operational status (saving the cost of maintaining limited life components while they are non-operational). The operational warheads are called the active stockpile (AS) and the non-operational warheads are called the inactive stockpile (IS).
The stockpile is subject to several uncertainties and associated risks, including the possibility of an unforeseen catastrophic failure of a class of delivery vehicles, warhead-type or family, or an unexpected reversal of the geopolitical situation that would require an increase in the number of weapons available for use. It is vital for the DoD and the NNSA to have procedures in place designed to mitigate these and other risks with a strategy that “hedges” against threats to the stability of the nuclear deterrent at lower stockpile levels.
There are two basic approaches to nuclear stockpile risk mitigation: the existence of a significant warhead production capability, the maintenance of warheads designated as hedge weapons, or some combination of the two. During the Cold War, the United States maintained a robust production capability to augment or decrease production, as required, depending on operational and geopolitical requirements. Today, the United States does not have an active nuclear weapon production capability and relies on the maintenance of a warhead hedge to reduce risk to acceptable levels.
In the absence of a modernized nuclear infrastructure and the reestablishment of a fissile component production capability (with sufficient capacity), the decision to reduce the size of the hedge and dismantle additional weapons is final and cannot be reversed. Once the weapons are gone, the total stockpile number is permanently decreased until the United States can produce replacements—using a production process whose construction and deployment time to a first weapon could take two decades or longer. Because of this, decisions regarding the U.S. nuclear weapons stockpile hedge are more complicated than they might seem and are being considered by U.S. policy makers at the highest levels. Hedge weapons are included in both the active and inactive stockpiles.
Active stockpile warheads are maintained in an operational status. These weapons undergo regular replacement of limited life components (e.g., tritium components, neutron generators, and power-source batteries), usually at intervals of a few years. AS warheads are also refurbished with all required life extension program (LEP) upgrades, evaluated for reliability estimates (usually every six months), and validated for safety (usually every year). AS warheads may be stored at a depot, stored at an operational base, or uploaded on a delivery vehicle (e.g., a re-entry body, a re-entry vehicle, an air-launched cruise missile, or a delivery aircraft).
Active stockpile warheads include: active ready warheads that are operational and ready for wartime employment; logistics warheads that provide the operational flexibility for military weapons technicians to switch, with minimum loss of operational time, a logistics warhead with an active ready warhead needing maintenance (e.g., for limited life component exchange (LLCE)) or selected for quality assurance testing; active near-term hedge warheads that serve as part of the technical or geopolitical hedge and can serve as active ready warheads within six months; and logistics warheads to support active near-term hedge warheads.
Inactive stockpile warheads are maintained in a non-operational status. IS warheads have their tritium components removed as soon as logistically practical, and the tritium is returned to the national repository. Other limited life components are not replaced until the warheads are reactivated and moved from the inactive to the active stockpile. Some IS warheads are refurbished with all required life extension program upgrades; others are not upgraded until the refurbishment is required for reactivation. Some IS warheads are evaluated for reliability estimates; other IS warheads may not require a reliability estimate. All IS warheads are validated for safety (usually every year). They are normally stored at a depot, not at an operational base. IS warheads are never uploaded on a delivery vehicle (e.g., a re-entry body, a re-entry vehicle, an air-launched cruise missile, or a delivery aircraft).
Inactive stockpile warheads include: inactive near-term hedge warheads that serve as part of the technical or geopolitical hedge and can serve as active ready warheads within six to 24 months; logistics warheads to support inactive near-term hedge warheads; Quality Assurance and Reliability Testing (QART) Replacement warheads (also known as Surveillance Replacement warheads); and extended hedge warheads that serve as either as part of the technical or geopolitical hedge and can serve as active ready warheads within 24 to 60 months.
The annual Requirements and Planning Document (RPD) provides the supporting details upon which the stockpile plan is based. The RPD uses a system of readiness states (RS) to determine what quantities of warheads require various programmatic activities.
RS levels determine quantities in five subcategories: RS-1 are active weapons located at an operational base or uploaded on operational delivery vehicles; RS-2 are active weapons stored at a depot; RS-3 are inactive weapons that require refurbishment, reliability estimates, and safety validation; RS-4 are inactive weapons that require reliability estimates and safety validation, but not refurbishment; and RS-5 are inactive weapons that require safety validation, but not refurbishment or reliability estimates. These RS levels are used as a management tool to ensure that only the required number of weapons receive component replacement and other programmatic actions; this helps to minimize the cost of maintaining, refurbishing, testing, and evaluating the nuclear stockpile.
The RS system also identifies quantities of warheads in four functional subcategories: A warheads are active ready and near-term hedge weapons; B warheads are logistics weapons; C warheads are QART Replacement weapons; and D warheads are extended hedge weapons. By using these functional sub-categories, government leaders and program managers can easily determine what quantities of weapons are required for each function. In the recent past, this has helped decision makers reduce total stockpile quantities and the cost of the U.S. nuclear deterrent more quickly, while avoiding a significant increase to the various risks associated with a rapid draw-down.
Logistical planning is necessary for configuration management to ensure components and weapons movements and locations match, as appropriate. Logistical planning includes plans for storing, staging, maintaining, moving, testing, and refurbishing weapons. Nuclear weapons logisticians must comply with requirements and restrictions from several sources, including joint DoD-DOE agreements and memoranda of understanding, Joint Publications (JPs) published by the Joint Chiefs of Staff, the Joint Nuclear Weapons Publications System (JNWPS), and Military Services’ Regulations. The key theme for logistical planning is to ensure that weapons are handled or stored in a way that they are always safe, secure, maintained to be reliable, and to preclude unauthorized acts or events.Storage
Storage refers to the placement of warheads in a holding facility for an indefinite period of time. Nuclear weapons are usually stored in secure, earth-covered bunkers, commonly called igloos (see figure 3.7) because of their near hemispherical appearance when observed from the outside. Logistical planning for nuclear weapons storage includes considerations for: the number of square feet required to store the designated warheads in each igloo so as to avoid criticality concerns, special barriers needed for safe separation of certain types of nuclear warheads, inside traffic flow for access to warheads by serial number (for maintenance or movement of a QART sample), procedures for allowing igloo access by official visitors, and security both at the igloo exclusion area and greater distances for the overall storage facility. Currently, storage of nuclear warheads occurs only at DoD facilities operated by the Navy and the Air Force. Some current U.S. nuclear weapons have been in storage at DoD facilities for decades. Storage is also a consideration for retired nuclear weapons awaiting dismantlement.Staging
Staging refers to the placement of warheads awaiting some specific function (e.g., transportation, disassembly, or dismantlement) in a holding facility for a limited period of time. Nuclear weapons are usually staged in secure, earth-covered igloos or in a secure staging area awaiting disassembly or dismantlement at the NNSA Pantex Plant near Amarillo, TX. Logistical planning for nuclear weapons staging includes all of the considerations mentioned above, as well as the planned flow of warheads in the disassembly/dismantlement queue. Staging of nuclear warheads occurs only at the NNSA Pantex Plant, and it occurs for a limited period of time (normally not more than several weeks). Many current U.S. nuclear weapons have been staged in the disassembly queue at least once as QART samples (where they were disassembled, had components tested and evaluated, and then reassembled for return to the stockpile); some warheads have been through that process several times.
Nuclear weapons maintenance includes the technical operations necessary to disassemble and reassemble a warhead to whatever extent is required for the replacement of one or more components. Maintenance operations require highly specialized training to qualify maintenance technicians. They also require special ordnance tools, technical manuals, and a secure and clean maintenance facility. Most maintenance operations, including limited life component exchanges, are performed by Navy or Air Force technicians at an appropriate military nuclear weapons maintenance facility. Some maintenance operations require the warhead to be disassembled to a greater extent than the military technicians are authorized to accomplish; in the event of such an occurrence, the warhead must be sent back to the Pantex Plant for maintenance.
For each type of warhead, the NNSA establishes a limited life component exchange schedule. This LLCE schedule is managed by individual warhead and by serial number, and it is coordinated with the appropriate military service and NNSA offices.
Warheads are moved for several reasons. For example, they may be selected as QART samples, or they may be moved within an operational base area. Warheads may also be moved to the Pantex Plant for disassembly, or they may be returned from Pantex after re-assembly. Warheads can be moved from an operational base to a depot upon retirement as part of the dismantlement queue and moved again to Pantex for dismantlement. On occasion, a warhead will be returned from the Military Service to Pantex because of a special maintenance problem. Normally, all warhead movements from one installation to another within the continental United States are accomplished using NNSA secure safeguards ground transport vehicles. The Air Force uses its own certified ground vehicles and security for moves within an operational base area. Movements of weapons to and from Europe are accomplished by the Air Force using certified cargo aircraft. LLCs may be transported by special NNSA contract courier aircraft or by NNSA secure safeguards ground transport. Representatives from agencies with nuclear weapons movement responsibilities meet frequently to coordinate the movement schedule.
The logistics aspects of the surveillance program include downloading, uploading, reactivating, and transporting warheads. For example, an active ready warhead selected at random to be a QART sample is downloaded from an ICBM missile. A logistics warhead is uploaded to replace the active ready warhead with minimum loss of operational readiness. The NNSA produces LLCs, which are sent to the depot; a QART replacement warhead is reactivated and transported by a secure safeguards vehicle to the operational base to replace the logistics warhead. The safeguards vehicle transports the QART sample warhead to Pantex for QART disassembly. After the QART testing is complete, the warhead may be reassembled and returned to the depot as an inactive warhead.
Logisticians plan and coordinate the dates and the required transport movements for each upload and download operation.
The United States remains committed to support NATO forces with nuclear warheads forward deployed in Europe. Recommendations for forward deployment are sent to the president as a Nuclear Weapons Deployment Plan. The president issues a classified Nuclear Weapons Deployment Authorization (NWDA) as a directive.
Once life extension program components are produced, the remaining actions are almost all logistical functions. These actions include the process through which the NNSA publishes changes to technical manuals, if required, transports the LEP components to the appropriate locations, disassembles the warheads, extracts the old components, inserts the new LEP components, reassembles the warheads, and transports them back to the appropriate Military Service.Retired Warheads
Warheads are retired from the stockpile by the Nuclear Weapons Council (NWC) in accordance with presidential guidance in the Nuclear Weapon Stockpile Plan. Retired weapons are shown as zero quantity in the NWSP covering the fiscal year in which they are retired. Retired weapons are not listed in subsequent NWSPs. Retired warheads fall into one of two categories:
Retired warheads released for disassembly are scheduled for disassembly consistent with the throughput available in NNSA facilities so as not to impact support for DoD requirements. (Currently, there is a significant backlog of weapons awaiting disassembly. Most of these warheads remain stored at DoD facilities because of limited staging capability in NNSA facilities.)
- Warheads pending approval for disassembly (weapons in “Managed Retirement”) must be maintained by the NNSA in such a way that they could be reactivated should a catastrophic failure in the stockpile necessitate such action. Weapons in managed retirement cannot be dismantled until approved by the Nuclear Weapons Council Standing and Safety Committee (NWCSSC).
The NNSA validates the safety of all retired warheads and reports annually to the NWCSSC until the weapons are dismantled. These annual reports specify the basis for the safety validation and may require additional sampling from the population of retired warheads.3.5 Nuclear Weapons Force Structure
The U.S. nuclear force structure includes both nuclear warheads, which have been discussed above, and the units that can deliver the nuclear warheads to a target, if and when approved by the president. These delivery units consist of the launch platforms, delivery vehicles, support equipment, and the personnel required to accomplish the employment mission. Among other things, the delivery units have a staff that supports the commander for various functions, such as human resources, intelligence, delivery operations, security, training, and supply. The units also have technical and operational procedures, a security system, and a personnel support system that provides for the care of the unit’s personnel. The remainder of this section will focus on nuclear delivery systems.3.5.1 Nuclear Weapon Delivery Systems
Nuclear weapons are carried to their targets through the use of nuclear weapon delivery systems. A nuclear weapon delivery system is the military vehicle (ballistic or cruise missile, airplane, or submarine) by which a nuclear weapon would be delivered to its intended target in the event of authorized use. Most nuclear warheads have been designed for specific delivery systems. The United States currently maintains a nuclear triad, or a system of delivery vehicles comprised of a sea, land, and air deterrent based on submarine-launched ballistic missiles, intercontinental ballistic missiles, and heavy bombers. Figure 3.8 depicts the U.S. nuclear triad.
The 2010 NPR concluded that, for planned reductions under the New START, the United States should retain a smaller triad of SLBMs, ICBMs, and heavy bombers. Retaining all three legs of the triad will best maintain strategic stability at a reasonable cost, while hedging against potential technical problems or vulnerabilities.
Weapons in the U.S. nuclear arsenal provide a wide range of options that can be tailored to meet desired military and political objectives. Each leg of the triad has advantages that warrant retaining all three legs in the near-term. Strategic nuclear submarines (SSBNs) and the SLBMs they carry represent the most survivable leg of the nuclear triad. Single-warhead ICBMs contribute to stability, and like SLBMs, have low vulnerability to air defenses. Unlike ICBMs and SLBMs, bombers can be visibly deployed forward as a signal in crisis to strengthen deterrence against potential adversaries and assurance of allies and partners; it is also possible to recall a manned bomber after launch or takeoff toward a target. Figure 3.9 is a list of the current U.S. nuclear warheads and their associated delivery systems.
Nuclear-powered SSBNs are designed to deliver ballistic missile attacks against assigned targets. These submarines carry submarine-launched ballistic missiles, which are the most survivable leg of the nuclear triad because of the ability of their SSBN delivery platforms to “hide” in the ocean depths, coupled with the long range of the missiles. Continuously on patrol, SSBN Trident missiles provide a worldwide launch capability, with each patrol covering a target area of more than one million square miles.
Each U.S. SSBN (Figure 3.10) is capable of carrying up to 24 Trident missiles. SSBNs are deployed from the west coast of the United States in Bangor, Washington, and from the east coast in Kings Bay, Georgia. These SSBNs carry the Trident II missile.
The 2010 NPR concluded that ensuring a survivable U.S. response force requires continuous at-sea deployments of SSBNs in both the Atlantic and Pacific oceans, as well as the ability to surge additional submarines in crisis. To support this requirement, the United States has 14 nuclear-capable Ohio-class SSBNs, of which 12 are operational at any one time, with the remaining two in long-term overhaul. By 2020, these Ohio-class submarines will have been in service longer than any previous submarines. As a prudent hedge, the Navy will retain all 14 SSBNs for the near term. To maintain an at-sea presence for the long term, the United States must develop a follow-on to the Ohio-class submarine. Because of the long lead times associated with the development and deployment of a new submarine, the secretary of defense has directed the Navy to begin technology development of an SSBN replacement immediately.
U.S. nuclear forces include intercontinental ballistic missiles, which are launched from stationary silos. ICBMs are on continuous alert, are cost-effective, can provide immediate reaction if necessary, and can strike their intended targets within 30 minutes of launch.
Currently, the U.S. ICBM force consists of Minuteman III (MMIII) missiles. MMIII missile bases are located at F.E. Warren Air Force Base (AFB) in Wyoming, Malmstrom AFB in Montana, and Minot AFB in North Dakota. Figure 3.11 shows a Minuteman III missile in a silo.
The United States has 450 deployed, silo-based MMIII ICBMs, each with one to three warheads. The 2010 NPR Report announced the U.S. decision to “deMIRV” all deployed ICBMs, so that each MMIII ICBM will have only one nuclear warhead. This step will enhance the stability of the nuclear balance by reducing the incentives for Russian preemptive nuclear attack or for U.S. launch under attack. The United States will continue the Minuteman III life extension program with the aim of keeping the fleet in service until 2030, as mandated by Congress. The Department of Defense will begin initial study of alternatives by Fiscal Year 2012, although a decision for a follow-on ICBM is not needed for several years. The study will consider a range of possible future options, with the objective of defining a cost-effective approach that supports continued reductions in U.S. nuclear weapons while promoting stable deterrence.
The U.S. bomber force serves as a visible, flexible, and recallable national strategic asset. The active U.S. inventory of B-52s (Figure 3.12), which are located at Barksdale Air Force Base in Louisiana and Minot AFB in North Dakota, has been the backbone of the strategic bomber force for more than 50 years. The B-52 “Stratofortress” is a heavy, long-range bomber that can perform a variety of missions. It is capable of flying at subsonic speeds at altitudes of up to 50,000 feet, and it can carry precision-guided conventional ordnance in addition to nuclear weapons. The B-52 is the only aircraft that can carry both gravity bombs and cruise missiles.
The B-2 “Stealth Bomber” (Figure 3.13) entered the bomber force in 1997, enhancing U.S. deterrent forces with its deep penetration capability. The B-2 is a multi-role bomber capable of delivering both conventional and nuclear munitions. The B-2 force is located at Whiteman AFB in Missouri.
The United States has 76 B-52 bombers and 18 B-2 bombers certified to deliver nuclear weapons. The 2010 NPR determined that the Air Force will retain nuclear-capable bombers, but it will convert some B-52s to a conventional-only role. The rationale behind retaining nuclear-capable (and dual-capable) bombers is twofold: first, this capability provides a rapid and effective hedge against technical challenges that might affect another leg of the triad and offsets the risks of geopolitical uncertainties; second, nuclear-capable bombers are important to maintain extended deterrence against potential attacks on U.S. allies and partners. The ability to forward deploy heavy bombers signals U.S. resolve and commitment in a crisis and enhances the reassurance of U.S. allies and partners, strengthening regional security architectures.
In addition to its strategic nuclear forces, the United States has CONUS-based and forward-deployed DCA consisting of the F-15 (Figure 3.14) and the F-16 (Figure 3.15). DCA are able to deliver conventional munitions or non-strategic nuclear bombs from the B61 family.
The United States also maintains forward-based DCA assigned to the U.S. European Command. Some of these DCA are available to support the North Atlantic Treaty Organization (NATO) in combined-theatre nuclear operations.
As discussed in the 2010 NPR Report, the Air Force is in the process of replacing its F-16s with the F-35 Joint Strike Fighter. The Air Force will retain a dual-capable fighter in the F-35, and it will also conduct a full scope B61 LEP to ensure that weapon’s functionality with the F-35. These decisions ensure that the United States will retain the capability to forward deploy non-strategic nuclear weapons in support of its commitments to its NATO allies.
The primary purpose of the U.S. nuclear force posture is to deter a nuclear attack against the United States, its allies, or its interests. If deterrence were to fail, the United States could employ its nuclear weapons. The decision to employ nuclear weapons at any level requires the explicit authorization of the president of the United States. The use of nuclear weapons represents a significant escalation from conventional warfare and involves many considerations. The fundamental determinant of action is the political objective sought in the use of nuclear or other types of forces. Together, these considerations have an impact not only on the decision to use nuclear weapons but also on how they are employed. Other prominent planning and employment factors include: the strategic situation, the type and extent of operations to be conducted, military effectiveness, damage-limitation measures, environmental and ecological impacts, and calculations concerning how such considerations may interact.3.6.1 Employment Guidelines and Planning Considerations
U.S. warfighters plan for the employment of nuclear weapons in a manner consistent with national policy and strategic guidance. The employment of nuclear weapons must offer a significant advantage over the use of non-nuclear munitions. Moreover, the complete destruction of enemy forces may not be required to achieve a desired objective; rather, containment and a demonstrated will to employ additional nuclear weapons toward a specific goal would be the preferred methods.
Planning for the use of nuclear weapons is based upon: knowledge of enemy force strength and disposition; the number, yields, and types of weapons available; and the status and disposition of friendly forces at the time that the weapons are employed. Employment planning considers the characteristics and limitations of the nuclear forces available and seeks to optimize both the survivability and combat effectiveness of these forces.
To provide the desired capabilities, nuclear forces must be diverse, flexible, effective, survivable, enduring, and responsive. If no one weapon system possesses all of the desired characteristics, a variety of systems may be necessary. Strategic stability and centralized control as well as command, control, communications, computers and intelligence (C4I) systems are important considerations in nuclear force planning and employment.
Targeting is the process of selecting targets and matching the appropriate weapon to those targets by taking account of operational requirements and capabilities. Targeting occurs and is performed at all levels of command within a joint force. Targeting includes the analysis of enemy situations relative to the military mission, objectives, and capabilities, as well as the identification and nomination of specific vulnerabilities that, if exploited, would accomplish the military purpose through delaying, disrupting, disabling, or destroying critical enemy forces or resources.
Targeting considerations include:
The inability of friendly forces to destroy targets using conventional means;
The number and type of individual targets;
The vulnerability of those targets, including target defenses;
The level of damage required for each target to achieve the overall objective;
The opponent’s ability to reconstitute or regenerate;
Avoidance of collateral damage; and
- Environmental conditions in the target vicinity including surface, upper air, and space conditions.
As reinforced in the 2010 Nuclear Posture Review Report, all U.S. ICBMs and SLBMs are “open-ocean targeted” so that, in the highly unlikely event of an accidental launch, the missile would land in the open ocean.3.7 Summary
While the United States has developed dozens of warhead-types and produced tens of thousands of weapons since the first atomic bomb explosion in 1945, the current stockpile has been drastically reduced—through unilateral and bilateral efforts—to its current size (5,113 warheads as of September 30, 2009). The composition of the existing U.S. nuclear stockpile is in part determined by the fact that no new U.S. nuclear weapons have been produced since 1991. Today’s stockpile is composed of nuclear warheads that are carried to their targets by one of a system of delivery vehicles that together comprise a sea, land, and air deterrent. The 2010 NPR concluded that this “nuclear triad” will be maintained into the foreseeable future, even as the United States continues to draw down its nuclear weapon stockpile in accordance with its treaty obligations and its stated intent to pursue a world free of nuclear weapons.
 The earliest U.S. nuclear weapons were distinguished by mark (MK) numbers, derived from the old British system for designating aircraft. In 1949, the MK 5 nuclear weapon, intended for the Air Force’s surface-to-surface Matador cruise missile and the Navy’s Regulus I cruise missile, had interface engineering considerations that were not common to gravity bombs. A programmatic decision was made to designate the weapon as a warhead, using the designation W5. At the programmatic level, the Project Officers Group (POG) and the agencies participating in the POG process distinguish between warheads and bombs. Weapons that have different engineering requirements because they must interface with a launch or delivery system are called warheads. Weapons that do not have these interface requirements, such as gravity bombs and atomic demolition munitions (now retired and dismantled), are called bombs. Using these definitions, the total number of U.S. nuclear weapons is equal to the sum of warheads plus bombs.
 Intercontinental missiles have a range capability that exceeds 5,500 kilometers. Ballistic missiles are those that do not rely upon aerodynamic surfaces to produce lift and consequently follow a ballistic trajectory (which may be guided or unguided) when thrust is terminated.
 SLBMs are any ballistic missiles capable of being launched by submarines; range capability is not a factor for this category.
 Heavy bombers are specified by aircraft type. Generally, heavy bombers have greater range capability and greater payload lift capacity than non-strategic aircraft.
 Combatant commanders and the Military Services determine the numbers and types of operational nuclear weapons required to satisfy national security policy objectives. These numbers, combined with National Nuclear Security Administration requirements and capacity to support surveillance, maintenance, and life extension, result in stockpile projections over time. These projections are codified in the annual Nuclear Weapons Stockpile Plan issued by the president. (See Appendix A: Nuclear Weapons Council and Annual Reports for information on the NWSP.)
 Tritium is a radioactive gas that is used in U.S. warheads as a boosting gas to achieve required yields. Because tritium is in limited supply and very expensive, special procedures are used to ensure that none is wasted in the process of storing, moving, and maintaining warheads. The national repository for tritium is at the Savannah River Plant, located near Aiken, SC.
 QART Replacement warheads are retained in the inactive stockpile to replace warheads consumed by the QART program or to provide replacement for a significant quantity of warheads planned to be unavailable for an extended period of time for QART evaluation.
 JNWPS is a system of technical manuals on nuclear weapons, associated materiel, and related components. It includes general and materiel manuals developed by the DoD and the DOE to provide authoritative nuclear weapons instructions and data.
 A “MIRVed” ballistic missile carries Multiple Independently Targetable Reentry Vehicles (MIRVs).
“DeMIRVing” will reduce each missile to a single warhead.
 There is no conventional or customary international law that prohibits nations from employing nuclear weapons in armed conflict. Therefore, the use of nuclear weapons against enemy combatants as well as against other military targets is lawful, if authorized by the president.