A 21st-Century Role for Nuclear Weapons

Atoms For Peace: Fifty Years Later


A 21st-Century Role for Nuclear Weapons

New security challenges and improved conventional weapons mean new roles and requirements for nuclear weapons.

The proliferation of weapons of mass destruction (WMD) has become a metaphor for 21st-century security concerns. Although nuclear weapons have not been used since the end of World War II, their influence on international security affairs is pervasive, and possession of WMD remains an important divide in international politics today.

Although the West had doubts about the military usefulness of nuclear weapons during the Cold War, archival evidence confirms that the Soviet Union would have used nuclear weapons from the outset had war broken out in Europe. Ironically, this has tended to support the view that the West’s nuclear posture over 40 years of rivalry with the Soviet Union actually had a stabilizing effect. This in turn may provide some explanation of the motives for the proliferation of WMD in the 21st century–a position that is bolstered by the futility of investment in conventional defense in light of advances in the military application of information technology in the United States and its principal allies.

The nuclear postures of the former Cold War rivals have evolved more slowly than the fast-breaking political developments of the decade or so that has elapsed since the former Soviet Union collapsed. Nevertheless, some important changes have already taken place. By mutual consent, the Anti-Ballistic Missile (ABM) Treaty of 1972 was terminated by the United States and Russia, which have agreed to modify their nuclear offensive force posture significantly through a large reduction in the number of deployed delivery systems. Nuclear weapons are no longer at the center of this bilateral relationship. Although the two nations are pursuing divergent doctrines for their residual nuclear weapons posture, neither approach poses a threat to the other. The structure, but not the detailed content, of the future U.S. nuclear posture was expressed in the 2002 Nuclear Posture Review (NPR), which established a significant doctrinal shift from deterrence to a more complex approach to addressing the problem of proliferated WMD.

The Russian doctrinal adaptation to the post-Cold War security environment is somewhat more opaque. The government appears to be focused on developing and fielding low-yield weapons that are more suitable for tactical use, though the current building of new missiles and warheads may be associated with new strategic nuclear payloads as well. Despite the diminished post­Cold War role of nuclear weapons in the United States, the cumulative deterioration of Russia’s conventional military force since 1991 has actually made nuclear weapons more central to that government’s defense policy.

The end of the adversarial relationship with the Soviet Union (and later, the Russian Federation) had to be taken into account in the NPR. The current nuclear posture is evolving in a manner parallel to the modernization of the U.S. non-nuclear military establishment. In stark contrast to Cold War­era military planning, the 21st century is likely to be characterized by circumstances in which the adversary is not well known far in advance of a potential confrontation.

The U.S. Department of Defense (DOD) is adjusting to these new circumstances by developing highly capable and flexible military forces that can adapt to the characteristics of adversaries as they appear. This makes the traditional path to modernization through investment in weapons systems as the threat emerges economically infeasible. Modern information technology lets the military change the characteristics of its flexible weapons and forces in much less time than it would take to develop whole new weapons systems. Thus, DOD is attempting to create a military information system: the integrated effect of command-control-communications-computation-intelligence-surveillance and reconnaissance (C4ISR). This system is inherently more flexible for adapting to changes in the threat environment.

These developments raise the question of what changes in the U.S. nuclear posture have been fostered by radical changes in the international security environment. In the 1990s, the United States selected eight (from the 32 in the inventory at the time) nuclear weapon types (with one additional type in reserve)–two for each of the four primary delivery systems [heavy bomber, cruise missile, land-based intercontinental ballistic missile (ICBM), and submarine-launched ballistic missile (SLBM)], to be preserved in perpetuity. The Stockpile Stewardship Program is developing a set of diagnostic and experimental facilities that will keep these eight weapons in the inventory indefinitely without sacrificing weapon safety and reliability. Most nuclear missions, apart from the area-destruction and shallow earth-penetration missions, were eliminated by these choices.

The NPR focuses on the limitations of applying weapons designed for the assured-destruction mission against the former Soviet Union to a much less predictable range of future adversaries and targets. The Bush administration concluded that it could dispense with thousands of weapons in the current stockpile, and it reached a bilateral agreement with Russia to institutionalize a reciprocal reduction in numbers of nuclear delivery systems and their associated nuclear payloads.

Thus, the need to be able to credibly produce (or threaten to produce) vast urban and industrial destruction in the 21st century has been sharply reduced. Moreover, the cumulative impact of information technology on U.S. non-nuclear capabilities has dramatically increased the ability to locate and destroy targets precisely. What role is left, therefore, for the unique properties of nuclear weapons–their intense nuclear and thermal radiation and extraordinary energy density–in a 21st-century security policy?

The 20th-century legacy

Coping with the threat of Soviet military power required a specialized nuclear posture in the 20th century. The concept of demonstrative use, in which a nuclear weapon would be used to intimidate rather destroy an enemy, that had characterized the early years of the nuclear program (1945­1953) was replaced with concepts that explicitly coupled nuclear weapons to military as well as political purposes. Nuclear weapons in the thousands were needed to meet the security requirements that evolved from the defense policy developed by President Eisenhower in the early part of 1953. Planners expected to replace these with more modern versions over time. The modern optimized designs at the leading edge of scientific knowledge would be lighter, smaller, safer, and more effective. But they would not be designed for an indefinite service life, and their safety and reliability were tied to manufacturing processes and technologies that turned out to be incompatible with future engineering, environmental, and occupational safety and health standards.

These circumstances during the Cold War created a need for a large integrated nuclear weapons design, engineering, testing, and manufacturing complex capable of continuous modernization and series production as well as support for an inventory of thousands of weapons. Technical problems that emerged over the life of the nuclear weapon could be resolved through explosive testing of nuclear munitions. The availability of funds to continually upgrade the nuclear weapons stockpile and the opportunity to test the weapons themselves contributed to high confidence in the safety and reliability of the deployed weapon systems. An added measure of confidence was created by the retention of large numbers of obsolescent or nondeployed weapons in the inventory, which served as a hedge against unanticipated problems in the ability of the manufacturing complex to deliver nuclear weapon components or to complete systems when required.

The nuclear weapons manufacturing complex was significantly scaled back after the end of the Cold War in the hope that only weapon remanufacturing rather than series production would be required in the future. Nevertheless, the need to support the Stockpile Stewardship Program in the face of requirements for preserving eight weapon types without explosive testing still required a large complex. Until the U.S. Senate rejected the Comprehensive Test Ban Treaty in 1999, there was a prohibition on nuclear testing and the development of new weapon designs with a yield of less than five kilotons. In response to the Senate rejection of the treaty, the Bush administration adopted a conditional readiness policy to resume testing if required, and new statutory authority has been granted to develop new weapon designs. However, avoiding or limiting requirements for testing is clearly preferred. Work is proceeding to develop several major diagnostic and experimental facilities that are aimed at simulating the nuclear explosive sequence without actual testing. These may also help reduce the cost and compress the time required to create new weapon designs or modify existing ones.

New designs that could be used on a number of different platforms could reduce the cost and the number of weapons that would have to be stockpiled.

The eight legacy weapons were designed for a specific set of military applications in support of a policy to deter a well-understood adversary. A series of bilateral initiatives successively reduced the possibilities for miscalculation. Yet the ability to limit damage from a nuclear attack in the event that deterrence failed was denied by treaty from 1972 to 2002.

The new security environment

WMD and the means to deliver them are mature technologies, and knowledge of how to create such capabilities is widely distributed. Moreover, the relative cost of these capabilities declined sharply toward the end of the 20th century. Today, the poorest nations on earth (such as North Korea and Pakistan) have found WMD to be the most attractive course available to meet their security needs. Proliferation of WMD was stimulated as an unintended consequence of a U.S. failure to invest in technologies such as ballistic missile defense that could have dissuaded nations from investing in such weapons. The United States’ preoccupation with deterring the Soviet Union incorporated the erroneous assumption that success in that arena would deter proliferation elsewhere. This mistake was compounded by the perverse interaction between defense policy and arms control in the 1990s. Misplaced confidence was lodged in a network of multilateral agreements and practices to prevent proliferation that contributed to obscuring rather than illuminating what was happening. Confidence placed in the inspection provisions of the Nuclear Non-Proliferation Treaty (NPT), for example, obscured efforts to obtain knowledge of clandestine WMD programs. NPT signatories were among those nations with clandestine WMD programs.

Without a modernization of defense policy, the ready availability of WMD-related technology will converge with their declining relative cost and a fatally flawed arms control structure to stimulate further proliferation in the 21st century. The process whereby WMD and ballistic missile technology has proliferated among a group of nations that otherwise share no common interests is likely to become the template for 21st-century proliferation.

The scope of this problem was recognized in part as a result of a comprehensive review of intelligence data in 1997­1998 by the Commission to Assess the Ballistic Missile Threat to the United States (the Rumsfeld Commission). This recognition swiftly evolved into a set of significant policy initiatives that responded to changes in the international security environment. The arms control arrangements most closely identified with the adversarial relationship with the former Soviet Union were passé. In 1999 the Senate refused to ratify the Comprehensive Test Ban Treaty; the United States and Russia ended the 1972 ABM Treaty and agreed to jettison the START process, which kept nuclear deployments at Cold War levels in favor of much deeper reductions in offensive forces in 2002.

U.S. policy began to evolve in response to these developments. The incompatibility between the Cold War legacy nuclear posture and the 21st-century security environment stimulated a search for approaches to modernize policies pertinent to nuclear weapons. In response to statutory direction, the Bush administration published the Quadrennial Defense Review, the Nuclear Posture Review, the National Defense Strategy of the United States, and the National Strategy to Combat Weapons of Mass Destruction. Taken together, these documents constitute the most profound change in U.S. policy related to nuclear weapons since the Eisenhower administration.

These policy documents in turn reflected the administration’s shift from a planning model based on specific threats (where military forces could be optimized against a known threat) to one based on capabilities. The administration sought to transform U.S. military capabilities to serve national policy in an environment where emerging threats would not provide warning to governments in enough time for them to replace their inventory with weapons systems suitable to the new threat.

The transformation aspirations reflected in the administration’s defense policy had a nuclear component as well, although the role of nuclear weapons would be much smaller than during the Cold War. Two new elements that were not part of Cold War strategic forces affected the role of nuclear weapons powerfully. The agreement to terminate the ABM treaty allowed ballistic missile defense to be introduced into the strategic equation. And the cumulative effect of advances in non-nuclear weapons (especially precision strike capability and information-intensive conventional military operations) dramatically expanded the ability of non-nuclear weapons to hold adversary strategic targets at risk throughout the threat cycle, thus diminishing the need to use nuclear weapons for this purpose.

Accuracy is now largely independent of the range of a weapons system, and increasingly persistent surveillance is available in almost every corner of Earth. Yet these capabilities can be delivered with a much smaller force structure today than previously. Advances in the military applications of information technology are letting the United States and similarly equipped allies substitute bandwidth (a proxy measure for information content) for force structure. Bandwidth used by military forces has increased by a factor of 100 since Operation Desert Storm in 1991, whereas the number of troops in U.S. forces has declined by one-third.

These capabilities allow a sharply focused military campaign to concentrate the application of military power on attacking targets (by electronic or kinetic means) in order to achieve specified military and political aims. This emphasis on effects-based military operations minimizes collateral damage, logistics requirements, and the duration of a conflict. All this has profound implications for the future role of nuclear weapons.

New weapons for new conditions

The unique capabilities of nuclear weapons may still be required in some circumstances, but the range of alternatives to them is much greater today. The evolution of technology has created an opportunity to move from a policy that deters through the threat of massive retaliation to one that can reasonably aspire to the more demanding aim–to dissuade. If adversary WMD systems can be held at risk through a combination of precision non-nuclear strike and active defense, nuclear weapons are less necessary. By developing a military capability that holds a proliferator’s entire WMD posture at risk rather than relying solely on the ability to deter the threat or use of WMD after they have been developed, produced, and deployed, the prospects for reducing the role of WMD in international politics are much improved.

Although a detailed discussion of the likely path of the problem of WMD proliferation is beyond the scope of this article, the macro trends are well known. The relative cost of procuring a WMD capability is declining, while the opportunities to conceal these programs (for example, through advanced tunneling technology to create underground development, manufacturing, and storage sites) are improving. A defense posture that makes it extremely difficult for a potential proliferator to reasonably expect that it will be able to field and use an effective WMD capability is more likely to dissuade him from acquiring such a capability in the first place.

An important dimension of the policy shift is the need to be able to hold WMD at risk before their operational use. A wide range of circumstances could produce the use or threat of use of such capabilities that might not necessarily be affected by deterrence alone. The need to preemptively target WMD capabilities is driven by the nature of these weapon systems. A single nuclear or biological weapon could produce tens or even hundreds of thousands of casualties.

The military capabilities needed to implement the new approach are formidable. Although the unique effects of nuclear weapons have a role in this policy under a narrow range of circumstances, the decisive enabler is a highly effective C4ISR system. The Defense Science Board described the capabilities and concepts of operation needed to implement this policy in its 2003 report The Future of Strategic Strike.

Because nuclear weapons may be required in certain circumstances to destroy biological pathogens, their effectiveness for this purpose must be evaluated.

The 21st-century proliferation problem creates a set of targets significantly different from those that existed during the Cold War. Few targets can be held at risk only by nuclear weapons, but the ones that are appropriate may require different characteristics and, in many circumstances, different designs than those currently in the nuclear stockpile. The nature of the targets and the scope of the potential threat also alter the character of the underlying scientific, engineering, and industrial infrastructure that supports the nuclear weapons posture. Some of the desirable characteristics of 21st-century nuclear weapons and the supporting infrastructure include the following:

Low maintenance. The current stockpile is based on nuclear weapon designs that have stayed in the inventory well beyond their anticipated life (the average age of the weapons in the stockpile is approximately 20 years). To maintain a high level of safety and reliability, costly and complex maintenance is required. Weapon designs that focus on achieving a high order of weapon safety and reliability with very low maintenance are needed.

Tailored effects. Nuclear weapon designs that provide an ability to attack a wide variety of targets, including biological weapons, heavily fortified and deeply buried targets, and other missions, are more appropriate than the present stockpile, which is designed primarily to attack targets across a wide area or hardened military targets on or near the surface.

Just-in-time development and manufacturing. The current complex is not responsive to the tempo of changes in the threat. This problem has been mitigated by keeping a nuclear weapons stockpile that is larger than operationally necessary. The development of a manufacturing complex that could create new designs (or modify existing ones) and manufacture weapons in the quantities needed when the threat emerges is more appropriate to 21st-century conditions.

Cross-platform warhead designs. The current stockpile incorporates two weapon designs for each of four types of delivery platforms (ICBM, SLBM, bomber, and cruise missile). Although stockpile diversity is a prudent hedge with the current stockpile, new designs that could be used on a number of different platforms could reduce the cost and the number of weapons that would have to be stockpiled.

High levels of safety and reliability. Weapon safety has always been a central issue of stockpile design, and the reliability of weapon performance could be maintained by cross-targeting and modernization. The terrorist threat makes it desirable to make weapons even safer and less vulnerable to unauthorized use, while always performing in a predictable and reliable manner, even in uses not contemplated when the weapons were designed.

No special delivery system requirements. Stockpile weapons are designed and optimized for a specific delivery system, and this was especially true for tactical aircraft. These airplanes required extensive modifications to be certified for nuclear delivery. In the future, nuclear weapons should be designed as much as possible to be independent of the platform used to deliver them.

Integration of nuclear weapons planning into conventional operations. The use of nuclear weapons was historically a specialized mission that was separate from conventional military operations (except in the case of North Atlantic Treaty Organization operations during the Cold War). Although strict control by the president over nuclear release is still a critical requirement, the planning process for 21st-century security requires that nuclear weapons be more integrated with advanced conventional weapons and forces.

Reuse of tested warhead designs where possible. Although only a few of the nuclear weapons developed during the Cold War were retained for the stockpile, a much larger number of fully developed and tested designs were created. Some of these designs could be reused, although some modifications are inevitable in both design and manufacturing as well as deployment modes to make them suitable for 21st-century needs.

Readiness to test new weapon designs, design modifications, or manufacturing process changes. The Senate decisively rejected a permanent ban on nuclear testing in 1999, reversing a policy in place since 1992. The Stockpile Stewardship Program may significantly diminish but will not wholly eliminate the need to test. Testing can materially add to confidence in a particular design in some circumstances, and there is a need to revive fundamental research in nuclear weapons physics.

Inclusion of the requirement to defeat biological weapons. Little is known about what is necessary to destroy biological weapon pathogens, but some analysis suggests that non-nuclear munitions may be ineffective. Because nuclear weapons may be required in certain circumstances to destroy biological pathogens, their effectiveness for this purpose must be evaluated.

It is impossible, of course, to permanently rule out a requirement for the sort of area destruction that was the hallmark of Cold War­era deterrence. Hence, there is likely to be an enduring requirement to retain a measure of this capability in the national inventory. In addition, although most targets are vulnerable to precision non-nuclear weapons, an irreducible subset of these targets can only be held at risk by the unique properties of nuclear weapons. In this respect, nuclear weapons are still vital to U.S. national security.

The refocusing of U.S. nuclear weapons policy and programs from the relatively narrow notion of deterrence to the broader aspiration of dissuasion has a better chance of working than the failed techniques of 20th-century nonproliferation policy: international norms, exhortation, and economic sanctions. Libya’s decision to abandon its own WMD programs in December 2003 after decades of obfuscation and clandestine investment suggests that at least some governments can be dissuaded from their efforts to acquire WMD by more direct and explicit threats to their WMD programs. Moreover, Libya’s decision has exposed a vast secret infrastructure of nuclear weapons technology and critical components involving, directly or indirectly, more than a dozen nations. This discovery will have to be considered in planning international efforts to limit proliferation.

It remains to be seen whether the Bush administration’s plan for combating WMD as will be successful. The integration of a modern global C4ISR system, advanced conventional weapons, and a modernized nuclear weapons development and manufacturing complex is a costly, prolonged, and complex affair; characteristics that are often difficult for democratic regimes to sustain. Nevertheless, the preliminary evidence suggests that the first quarter of the 21st century may offer the best hope for recreating international norms against WMD proliferation.

William Schneider, Jr., (william.schneider@osd.mil) is chairman of the Defense Science Board of the Department of Defense.