U.S. Nuclear Policy at an Inflection Point

U.S. nuclear policy faces a moment of great change and consequential decisions that will influence Washington’s approach to nuclear deterrence and strategy for many years to come. The United States is pushing ahead with a massive nuclear modernization plan that includes new delivery systems (missiles, submarines, aircraft, etc.) and new nuclear warhead designs. Given the multi-decade service lives of these weapons systems, the spending choices made over the next decade will determine the shape of the U.S. nuclear arsenal for a long time. The arsenal’s composition will subsequently impact U.S. nuclear strategy and its approach to arms control by creating sunk costs. Now is therefore the time to reconsider the role of nuclear weapons in U.S. strategy and foreign policy.

The U.S. modernization plan’s moment of truth coincides with important structural changes in the international system that will impact nuclear policy. Nearly three decades of U.S. military and economic primacy are slowly coming to an end. The U.S.-China relationship is on a dire trajectory; the need for a drawn out “great power competition” with Beijing is fast becoming a rare bipartisan point of agreement in Washington. This shift toward confrontation does not bode well for arms control agreements that previously served as important guardrails for nuclear competition. Moreover, advances in long-range precise conventional weapons, missile defense systems, and emerging technology like artificial intelligence will add new wrinkles to the already difficult task of deterrence by giving states non-nuclear tools to disrupt their adversary’s nuclear forces.

In this transformative period, it is imperative to return to first-order questions about the purpose of nuclear weapons in U.S. strategy and foreign policy. What kinds of threats does the United States use nuclear weapons to counteract? Are U.S. leaders expecting nuclear weapons to do too much or assigning qualities to nuclear weapons that they may not have? Washington has not grappled with fundamental questions like this since the end of the Cold War, but the magnitude of the various changes affecting nuclear policy demand fresh thinking and new answers. Forging ahead with detailed adjustments to the nuclear arsenal or making fine-tuned adjustments to strategic deterrence without contending with first-order questions is a recipe for bad policymaking that could have catastrophic consequences.

The Times They Are a Changing

American policymakers face the unenviable task of trying to craft nuclear policies and set the foundation for the future of the U.S. nuclear arsenal concurrent with major changes in international politics. The three shifts that will affect U.S. nuclear policy the most are changing U.S. threat perceptions, the erosion of traditional arms control agreements, and the rise of non-nuclear strategic technologies. Taken together, these forces of change should prompt a reexamination of the first-order questions that animate U.S. nuclear policy.

The international threats facing the United States are the primary driver of its nuclear policy, which includes U.S. arms control, deterrence, and nuclear force posture issues. The Cold War’s global struggle between the United States and Soviet Union presented a very challenging yet narrowly defined nuclear threat. The Soviet Union was the primary threat, and U.S. nuclear policy was completely geared toward the communist superpower. Details of nuclear policy changed throughout the Cold War to adjust to new developments in the U.S.-Soviet balance, but these adjustments did not represent fundamental rethinking of the primary threat or the role of nuclear weapons in responding to it. The condition of mutual assured destruction produced a relatively stable nuclear balance and both superpowers were highly sensitive to any effort by the other to break out of mutual vulnerability. While each superpower attempted to adjust the nuclear balance in their favor, these efforts were closely monitored and quickly countered by the other side.

The Soviet Union’s collapse created a new threat environment and U.S. nuclear policy changed with it. While Russia remained America’s only nuclear peer in terms of number of warheads, the improving relationship between them meant that both could make reductions in their arsenals with less trepidation. New nuclear weapons states like India, North Korea, and Pakistan raised concerns about nuclear weapons in “regional” conflicts, and the Global War on Terror prompted threat inflation about the possibility of a nuclear terror attack against the United States. Washington’s fear of weapons of mass destruction in the hands of “rogue states” was an important driver of U.S. foreign policy in the post–Cold War period. Ironically, the military operations the United States conducted to deal with this fear may have encouraged more states to seek nuclear weapons as a form of regime survival insurance.

While there has not been a precipitous change in the global balance of power on the magnitude of the collapse of the Soviet Union, a slow but steady weakening of America’s dominant position in the world is underway. The Trump administration’s emphasis on “great power competition” will persist in Washington even if he loses the 2020 election due to strong bipartisan support for a more competitive U.S. strategy that can counter both China and Russia. Nuclear policy is already starting to play a prominent role in this new threat environment. The U.S. nuclear modernization plan, originally put in motion by the Obama administration prior to the new focus on great power competition, is frequently portrayed as a necessary reaction to similar Russian and Chinese efforts to improve their own nuclear arsenals. Certain arms control agreements, such as the Intermediate-Range Nuclear Forces Treaty, which were regarded as stabilizing in previous threat environments, are now decried as too restrictive and limiting. For the time being, the world is unlikely to return to the kind of nuclear arms racing associated with the last period of competition between nuclear-armed great powers, but a general shift toward a more assertive U.S. nuclear policy is well underway.

A general erosion of arms control is making this new threat environment more dangerous. American withdrawals from the Anti-Ballistic Missile Treaty (2002), the Intermediate-Range Nuclear Forces Treaty (2019), and the Open Skies Treaty (2020) leaves the New Strategic Arms Reduction Treaty (New START) as the last U.S.-Russia arms control treaty in effect. New START will expire unless extended by February 2021. While Moscow has indicated its willingness to extend the treaty, the Trump administration is insisting on conditions for extension, namely the inclusion of China in a follow-on agreement, which remain unresolved.

Multilateral arms control agreements are also in trouble. The United States withdrew from the Iran nuclear deal in the summer of 2018 despite the agreement’s success at reducing Iran’s capacity to create a nuclear weapon. The other parties to the Iran deal have tried to keep it alive despite U.S. actions, but the damage to multilateral arms control caused by America’s withdrawal will be hard to reverse. The international Non-Proliferation Treaty (NPT) is not at risk of outright collapse, but intensifying nuclear competition among the great powers and damage to other arms control agreements are making it harder for NPT members to reach consensus and make progress on new initiatives. Some countries and civil society groups, frustrated at the lack of progress on nuclear disarmament that the NPT was supposed to encourage, created the Treaty on the Prohibition of Nuclear Weapons, which was adopted by the United Nations in July 2017. This new treaty was not created to weaken the NPT, but it may inadvertently make consensus among NPT states harder to achieve by underscoring the differences between nuclear haves and have nots.

The final structural change that impacts U.S. nuclear policy is the growth of non-nuclear strategic technologies. These are military capabilities that can hold targets at risk that previously could only be reliably held at risk by nuclear weapons, thereby blurring old dividing lines between nuclear and conventional war. For example, improvements in conventional missile accuracy and speed give them a much greater probability to destroy command and control facilities or mobile nuclear forces. Going after the same targets in the Cold War might have required using a nuclear weapon that could make up for lower accuracy with greater explosive power and a wider area of damage. In the Cold War scenario, using a nuclear weapon to target command and control or mobile nuclear forces guaranteed a response in kind, but in future conflicts the destruction of a country’s nuclear arsenal may not require the attacker to cross the nuclear threshold first. Precise conventional weapons cannot fully substitute for nuclear weapons—there are some targets that can only be reliably destroyed by a nuclear explosion—but even a small degree of substitution makes escalation harder to control.

Another worrying aspect of non-nuclear strategic technologies is their role in both conventional and nuclear operations. This conventional-nuclear entanglement is perhaps most noticeable in outer space. Modern militaries depend on satellites to provide secure communications, information about enemy movements, and early warning to protect against missile attacks. However, many of these satellites, especially in the U.S. military, also play roles in nuclear command and control or early warning. In a military conflict, an adversary would have a strong incentive to destroy or disable these satellites because of their important role in conventional missions but doing so would also impact the target’s nuclear systems.

Returning to First-Order Questions

The changing international environment and new, technology-based challenges to nuclear stability should encourage a wholesale reexamination of U.S. nuclear policy. The nuclear modernization plan’s timeline means that this reexamination needs to happen soon before programs advance further and create path dependency and sunk costs. Nuclear policy debates can quickly become bogged down in technical or budgetary minutiae instead of fundamental issues about the role and purpose of nuclear weapons. Returning to first-order questions is always good practice when crafting nuclear policy, but it is especially important in the current moment of a shifting international balance of power.

A good starting point for grappling with these questions is asking about the role of nuclear policy for accomplishing broader U.S. foreign policy goals. Put differently, what does the United States use nuclear weapons to do, and what kind of threats do they deter?

The United States is fond of expansive and maximalist foreign policy goals in general, and its current nuclear policies reflect this tendency. All nuclear-armed states, including the United States, use their arsenals to deter nuclear attack on their territory, and current U.S. nuclear policy easily accomplishes this fundamental task of deterring a first strike. However, the United States is the only country that currently practices extended deterrence, which entails using U.S. nuclear weapons to prevent both nuclear and, in the words of the 2018 Nuclear Posture Review, “significant non-nuclear strategic attacks” against allied countries that do not possess their own nuclear weapons. The three goals of U.S. extended deterrence are preventing nuclear attacks on allies, preventing conventional attacks on allies, and reassuring allies so they don’t feel the need to obtain nuclear weapons. Extended deterrence has been an important pillar of U.S. nuclear policy since the early Cold War, and the American “nuclear umbrella” is credited with discouraging many friendly countries from launching their own weapons programs. These great expectations for U.S. nuclear weapons create a demand for a diversified, flexible arsenal that can be called upon to prevent a wide range of scenarios.

The Trump administration seems content to accept this familiar answer to the question of what threats U.S. nuclear policy is meant to deter. In fact, the administration has placed a greater burden on the U.S. nuclear arsenal by disdaining arms control treaties that would otherwise provide a degree of predictability or restraint in potential adversaries’ behavior. The chief problem with this approach is that it demands U.S. nuclear weapons to do far too much. Preventing nuclear attack on the United States and its allies is a relatively easy lift, but the growth of non-nuclear strategic technologies makes it harder for nuclear weapons to deter lower-intensity forms of conflict. Moreover, the conventional-nuclear entanglement associated with these new capabilities will challenge U.S. nuclear policies designed to prevent conflicts from escalating to large-scale nuclear war.

This raises another question: If U.S. leaders are asking too much of nuclear weapons, how can they reduce the demands placed on nuclear policy? It is important to remember that deterrence is about preventing a state from doing something by increasing the costs or risks of them acting. Nuclear weapons can deter some actions very easily, while their value for deterring other actions is minimal or nonexistent. Shortening the list of actions that U.S. nuclear policy is expected to deter would be a good first step.

Deterring nuclear attack on American and allied territory should be the primary focus of U.S. nuclear policy. Responsibility for deterring lower-intensity forms of conflict should fall squarely on conventional capabilities. Ideally, friendly countries would be able to use such capabilities to provide a more robust self-defense posture that reduces the need for U.S. intervention. Given the shifts in non-nuclear strategic technology, smaller states can do more to deter larger states from attacking them even without resorting to nuclear weapons.

Finally, U.S. nuclear policy must accept the reality that shifts in the global balance of power require more limited, achievable objectives. If great power competition is the true top priority, then the United States must abandon maximalist demands on less important threats. The Iranian and North Korean nuclear programs are two examples where more reasonable nuclear policy goals are badly needed. The Iran nuclear deal required the United States to compromise on some of its objectives, but it reduced the threat of a nuclear-armed Tehran at the negotiating table instead of on the battlefield. Dropping demands for North Korea’s complete denuclearization and focusing instead on arms control and nuclear risk reduction would still accomplish the U.S. goal of reducing the North Korean nuclear threat. Creative, diplomatic approaches to reducing nuclear risks from minor powers would allow the United States to focus its attention on the more difficult task of preventing conflict among the great powers.


The world is changing, and U.S. nuclear policy needs to change with it. Policymakers need to ask some difficult, fundamental questions about the purpose of the nuclear arsenal before sinking more money into a multi-decade nuclear modernization plan that will cost over a trillion dollars. Renewed focus on great power competition makes it tempting to return to old nuclear policies that served the United States well in the past. However, assigning nuclear weapons greater responsibility for countering new threats is not the right approach. There is still time to right the ship of U.S. nuclear policy before the modernization plan creates path dependency and sunk costs that will make change harder. Hopefully this Cato Unbound edition will make a positive contribution to these important policy debates.

Also from this issue

Lead Essay

  • Eric Gomez argues that U.S. nuclear strategy is due for a reconsideration. As the U.S. stockpile of nuclear weapons undergoes modernization—a process that will take more than a decade—the time is right for rethinking what we should be doing with them. Gomez argues against relying too heavily on nuclear deterrence, which increases the risk that nuclear weapons will be used and makes them more attractive to countries that lack them.

Response Essays

  • Oriana Skylar Mastro argues that the United States government must achieve two significant goals in its nuclear weapons policy: First, it must prevent strategic competition with China from devolving into a nuclear arms race; and second, it must pave the way for nuclear arms control, ideally in conjunction with a reluctant Russia.

  • Beatrice Fihn calls attention to another aspect of current nuclear weapons policy debate—the growing movement to prohibit nuclear weapons entirely. Some 45 countries have ratified the Treaty on the Prohibition of Nuclear Weapons, just five short of the number required for ratification, and those party to the treaty will exert increasing pressure on the rest of the world to eliminate nuclear weapons entirely.

  • Michael Kofman argues for the continuing importance of Russia to U.S. nuclear strategy. Rather than a return to the Cold War, or a buy-all-you-can spending spree, Kofman argues for paying close attention to Russia’s own strategic planning, which requires much more attention than Russia’s headline-grabbing new weapons systems.