U.S. Nuclear Weapons Capability

U.S. nuclear weapons have played a critical role in preventing conflict between major powers since the end of World War II. Given their ability to deter large-scale attacks that threaten the U.S. homeland, allies, and forward-deployed troops and to assure allies and partners, nuclear deterrence has remained the number one U.S. national security mission.

Operationally, all U.S. military operations rely on the backstop of U.S. nuclear deterrence. It is therefore critical that the United States maintain a modern and flexible nuclear arsenal that can deter a diverse range of threats from a diverse set of potential adversaries.

Today, U.S. nuclear forces face three great challenges:

  • Aging nuclear warheads, their associated delivery systems, and systems for their command and control;
  • An aging and crumbling nuclear weapons infrastructure; and
  • An aging workforce.

The United States must fully recapitalize all three legs (land, air, and sea) of the nuclear triad including the systems for nuclear command and control while also conducting timely and cost-efficient warhead life-extension programs—all while operating under the current nuclear testing moratorium. Despite these challenges, the United States must ensure that its nuclear capabilities are sufficient to address the rising nuclear threat for the decades to come.

For the first time in history, the United States must deter two nuclear peers—Russia and China—while contending with a larger number of nuclear weapons states. Russia is engaged in an aggressive nuclear buildup, having added several new nuclear systems to its arsenal since 2010. The United States is only beginning to modernize its existing nuclear systems, but Russia’s modernization effort is about 86 percent complete.

Russia is also developing “novel technologies,” such as a nuclear-powered cruise missile and nuclear-capable unmanned underwater vehicle, and arming delivery platforms with nuclear-tipped hypersonic glide vehicles.

In addition, Russia maintains a stockpile of at least 2,000 non-strategic nuclear weapons, unconstrained by any arms control agreement. Lieutenant General Robert Ashley, Director of the Defense Intelligence Agency, has said that Russia is expected to increase this category of nuclear weapons—a category in which it “potentially outnumber[s]” the United States by 10 to 1.

This disparity is of special concern because Russia’s recent nuclear doctrine indicates a lower threshold for use of these tactical nuclear weapons. According to the 2018 Nuclear Posture Review (NPR), Moscow “mistakenly assesses that the threat of nuclear escalation or actual first use of nuclear weapons would serve to ‘de-escalate’ a conflict on terms favorable to Russia.”

China is engaging in what Admiral Charles A. Richard, Commander of U.S. Strategic Command (STRATCOM), has described as a “breathtaking” expansion of its nuclear capabilities as it attempts to project power into the South China Sea and throughout the world. China is well on its way to more than doubling its nuclear stockpile by the end of the decade. It is deploying advanced intercontinental ballistic missiles (ICBMs), completing its nuclear triad with the addition of a strategic nuclear-capable bomber, and deploying numerous theater-range ballistic missiles in the Indo-Pacific that can strike U.S. bases and allied territory with precision. Satellite imagery has also detected three ICBM silo construction sites in China that could hold at least 100 ICBM silos each.

STRATCOM has described this expansion as a “strategic breakout” and has stated that China’s nuclear capabilities will eventually exceed those of Russia.

Current U.S. nuclear posture is not designed to deter two peer nuclear threats.

Evidence also suggests that China is shifting a portion of its nuclear forces to Launch-on-Warning posture as it improves its early warning systems. Combined with a refusal to discuss its forces or intent with the United States, this shift in posture increases the likelihood of mistakes and miscalculations.

As current U.S. nuclear capabilities continue to age, the advancing nuclear threat increases the importance of nuclear weapons to U.S. national security. Noting this rapid deterioration of the threat environment since 2010, the 2018 NPR outlined four enduring roles for U.S. nuclear capabilities:

  • Deterrence of nuclear and non-nuclear attack;
  • Assurance of allies and partners;
  • Achievement of U.S. objectives if deterrence fails; and
  • Capacity to hedge against an uncertain future.

To achieve these objectives, the U.S. nuclear portfolio must balance the appropriate levels of capacity, capability, variety, flexibility, and readiness. Deterrence in a multipolar world is more complicated than in a bipolar world, as it requires a U.S. nuclear force capable of deterring multiple separate adversaries at the same time. What matters most in deterrence is not necessarily what the United States thinks will be effective. What matters most are the psychological perceptions—among both allies and adversaries—of America’s willingness to use nuclear forces to defend its interests. If an adversary believes that he can fight a limited nuclear war, for instance, U.S. leaders must convince that adversary otherwise. In addition, military roles and requirements for nuclear weapons will differ from adversary to adversary based on each country’s values, strategy, and goals.

Finally, U.S. nuclear capabilities must have the capacity to hedge against an uncertain future. Nuclear weapon capabilities take years or decades to develop, as does the infrastructure supporting them—an infrastructure that the United States has neglected for decades until quite recently. Decisions regarding nuclear forces made today will impact the United States decades into the future. Since the United States cannot predict what the level of the threat will be decades in the future, it is critical that the U.S. maintain a nuclear enterprise that can respond to changes in the global security environment.

A robust, well-resourced, focused, and reliable nuclear enterprise that is able to respond to unforeseen contingencies is itself an important piece of deterrence and will enable a nuclear force that is resilient and adaptable. The U.S. nuclear enterprise today, however, is largely static, leaving the United States at what could well be a technological disadvantage. Such a posture puts the security of the United States, the security of its allies, and the entire free world at risk.

Challenges to Maintaining Nuclear Forces

To provide assurance against failures in the U.S. stockpile or changes in a geopolitical situation, the United States must maintain the ability to adjust its nuclear force posture. To this end, the United States maintains an inactive stockpile that includes near-term hedge warheads that “can serve as active ready warheads within prescribed activation timelines” and reserve warheads that can provide “a long-term response to risk mitigation for technical failures in the stockpile.”

The United States preserves upload capability on its strategic delivery vehicles, which means that the nation could increase the number of nuclear warheads on each type of its delivery vehicles. For example, the U.S. Minuteman III ICBM can carry up to three Mk12A/W78 nuclear warheads, although it is currently deployed with only one.

Certain modernization decisions (e.g., 12 versus 14 Columbia-class ballistic missile submarines with 16 rather than 24 missile tubes per submarine) will somewhat limit upload capacity on the strategic submarine force. U.S. heavy bombers will continue to retain a robust upload capability that can be used if a geopolitical or technical emergency requires more deployed nuclear warheads.

The United States has not designed or built a nuclear warhead since the end of the Cold War. Instead, the National Nuclear Security Administration (NNSA) uses life-extension programs (LEPs) to extend the service lives of existing weapons in the stockpile, some dating back to the 1960s. Not all of the existing inactive stockpile, however, will go through a life-extension program. Consequently, our ability to respond to contingencies by uploading weapons kept in an inactive status will inevitably decline with the passage of time.

In addition, while LEPs replace or upgrade most components in a nuclear warhead, all warheads will eventually need to be replaced because their nuclear components—specifically, plutonium pits that comprise the cores of warheads—are also subject to aging.

It is therefore unwise for the United States to rely solely on LEPs to sustain needed levels of reliability. Moreover, the United States is the only nuclear state that lacks the capability to produce plutonium pits in quantity. An effort is underway to restart plutonium pit production, but various challenges have been encountered that could upset U.S. plans to sustain its nuclear weapons.

Part of the U.S. hedge against uncertainty in deterrence is the ability to conduct a nuclear test if testing is ever required to ensure the safety and reliability of U.S. warheads. Presidential Decision Directive-15 (PDD-15) requires the United States to maintain the ability “to conduct a nuclear test within 2–3 years” of direction by the President.

However, “the steady degradation” of test readiness after three decades of no testing calls into question the U.S.’s ability to meet this goal.

The lack of congressional interest in funding any significant improvements in test readiness further undermines efforts by the NNSA to comply with the directive.

The nuclear weapons labs also face demographic challenges. Most scientists and engineers with practical hands-on experience in nuclear weapons design and testing are retired. This means that the certification of weapons that were designed and tested as far back as the 1960s depends on the scientific judgment of designers and engineers who have never been involved in either the testing or the design and development of nuclear weapons. According to former NNSA Administrator Lisa Gordon-Hagerty, more than 40 percent of the NNSA workforce will be eligible for retirement over the next five years, further adding to the loss of legacy nuclear weapons knowledge.

The Stockpile Responsiveness Program (SRP), mandated by Congress and being implemented by NNSA, has been effective in exercising critical nuclear weapons design and development skills not fully exercised since the end of the Cold War. It is essential that those skills are available when needed to support modern warhead development programs for U.S. submarine-launched ballistic missiles (SLBMs) and ICBMs.

The shift in emphasis away from the nuclear mission after the end of the Cold War led to a diminished ability to conduct key activities at the nuclear laboratories. According to former Acting Administrator Dr. Charles Verdon:

The U.S. nuclear weapons stockpile is currently safe, secure, and militarily effective. However, the legacy stockpile systems are aging, and NNSA’s production infrastructure has atrophied considerably. America must invest in the weapons and infrastructure modernization programs to provide the capabilities needed to ensure the deterrent’s viability into the future. Future American political leaders will not have the weapons and infrastructure in place to support the nuclear arsenal unless we reestablish that capability now.


The need to modernize the nuclear weapons stockpile and recapitalize the supporting infrastructure needed to produce and maintain that stockpile has reached a tipping point. Approximately 60 percent of NNSA’s facilities are more than 40 years old and more than 50 percent are in poor condition. Assessments of facilities throughout the enterprise have identified numerous single-point failures. Production capabilities allowed to lapse are needed once again and reestablishing these capabilities is both a priority and a challenge.  If not appropriately addressed, the age and condition of NNSA’s infrastructure will put at risk NNSA’s missions, and the safety of its workforce, the public, and the environment.

As a result of this neglect, at the same time the nation faces a great challenge in modernizing its aging nuclear warheads, “NNSA is undertaking a risk-informed, complex, and time-constrained modernization and recapitalization effort.”

Assessing U.S. Nuclear Weapons Capabilities

Assessing the state of U.S. nuclear weapons ‌capabilities presents at least three serious difficulties.

  • The United States has not taken full advantage of technologically available developments to field modern warheads (often incorrectly termed “new” warheads) that could be designed to be safer, more secure, and more effective and could give the United States better options for strengthening a credible deterrent. Instead, the United States has largely elected to extend the life of aging nuclear warheads based on designs from the 1960s, 1970s, and 1980s that were in the stockpile when the Cold War ended.
  • The lack of detailed publicly available data about the readiness of nuclear forces, their capabilities, and the reliability of their weapons makes analysis difficult.
  • The U.S. nuclear enterprise has many components, some of which are also involved in supporting other military (e.g., conventional) and extended deterrence missions. For example, U.S. strategic bombers perform a significant conventional mission and do not fly airborne alert with nuclear weapons today, as they did routinely during the 1960s, nor stand at quick-reaction strip alert as they did up until the early 1990’s.

Additionally, the three key national security laboratories no longer focus solely on the nuclear weapons mission; they also focus extensively on nuclear nonproliferation and counterproliferation, intelligence, biological/medical research, threat reduction, and countering nuclear terrorism, which includes a variety of nuclear-related detection activities. Moreover, the Nuclear Command, Control, and Communications System entails many assets such as early warning and communications satellites that serve non-nuclear missions, such as routine military communications and detecting and tracking conventional missiles.

Thus, it is hard to assess whether any one piece of the nuclear enterprise is sufficiently funded, focused, and/or effective with regard to the nuclear mission.

The U.S. nuclear weapons enterprise is composed of several key elements that include warheads; delivery systems; and the physical infrastructure that designs, manufactures, and maintains U.S. nuclear weapons. The nuclear enterprise also includes and must sustain the talent of people: the nuclear designers, engineers, manufacturing personnel, planners, maintainers, and operators who help to ensure a nuclear deterrent that is second to none. The nuclear weapons enterprise entails additional elements like nuclear command and control; intelligence, surveillance, and reconnaissance; and aerial refueling, all of which also play a major role in conventional operations.

The selected factors are judged on a five-grade scale that ranges from “very strong,” defined as meeting U.S. national security requirements or having a sustainable, viable, and funded plan in place to do so, to “very weak,” defined as not meeting current security requirements and with no program in place to redress the shortfall. The other three possible scores are “strong,” “marginal,” and “weak.” That being said, this score of “strong” with a conditional trend toward “marginal” or “weak” reflects a greater risk than in previous years of a degradation in nuclear deterrence. Current forces are assessed as reliable today, but nearly all components of the nuclear enterprise are at a tipping point with respect to replacement or modernization and have no margin left for delays in schedule. Failure of on-time appropriations and lack of Administration support for nuclear modernization could lead to a rapid decline in this portfolio to “weak” in future editions.


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