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Over the past four years, many Americans have been surprised to learn that a U.S. president can order a nuclear strike at a moment’s notice without the approval of any other official. Though the president might be expected to consult with top military advisers, Congress or U.S. intelligence, there is no requirement that he or she do so. As long as the order can be certified as coming from the president, and as long as military officials involved in implementing the decision do not object to the order as violating the law of armed conflict, U.S. forces are expected to carry out the order.
Several members of Congress and experts have offered proposals to revise nuclear authorization procedures to require the approval of additional officials prior to the release of nuclear weapons. This would be an important step in improving the system, but it does not exhaust the changes needed to ensure the system serves U.S. interests. If and when the United States revises its policies on nuclear use authority, it should also address two other outstanding issues: ensuring that procedures are in place for the president to consult with the leaders of allied countries prior to ordering a nuclear operation that would affect them and reviewing the process by which the military would assess the legality of nuclear operations under the law of armed conflict.
Providing for Consultations With Allies
Allied countries may also be surprised to learn that there is no requirement for a U.S. president to consult them before using a nuclear weapon in their defense. Even worse, the existing communications systems and expectations that govern the current U.S. procedure for authorizing nuclear use may make it very difficult to have these consultations, even if a president wanted to. The existing system raises the risk that a president’s decision about whether to use a nuclear weapon could be based on incomplete information or could contradict the interests or wishes of U.S. allies. As the United States revises its policies on nuclear use authority, it should also ensure that procedures are in place for the president to consult with the leadership of affected allied countries.
Any detonation of a nuclear weapon near an ally’s territory will have tectonic effects on the ally’s interests. The blast—whether from a U.S. weapon or from an adversary responding to U.S. use—could cause radiation, thermal or blast damage to allied infrastructure, troops, civilians or natural resources. If the United States chooses to use a nuclear weapon in the context of a limited regional conflict, the likeliest context for nuclear use, it could disrupt the operations of allied forces or could shift the outcome of that conflict. Doing so could transform that ally’s relationships with regional partners or adversarial neighbors, especially if they think the ally approved nuclear use, and it could have complex and lasting consequences if domestic political groups criticize the allied government or its alliance with the United States for the event. At worst, U.S. nuclear use could inadvertently leave an ally angry, weakened and isolated.
For all of these reasons, a U.S. president has a strong interest in consulting with an allied leader prior to deciding whether to use a nuclear weapon. An ally is likely to have crucial information about the probable consequences of nuclear use that could affect the U.S. president’s decision. Furthermore, the president and U.S. military leaders may need to coordinate with an ally on a range of matters related to the decision—how allied forces can reduce the need to employ a nuclear weapon, how they can ensure nuclear and conventional operations will remain effective after nuclear use, how employment can contribute to winning a regional conflict after nuclear use, and whether allied civilians and infrastructure can be kept safe from U.S. use or expected adversary responses, including further nuclear escalation.
As a matter of principle, U.S. allies deserve to be consulted in U.S. nuclear use decisions whenever possible. While some allied officials worry that the United States might not use a nuclear weapon if needed, others worry that a president could use a nuclear weapon in a situation in which they believe it isn’t necessary. Some officials in allied countries flatly reject the idea that the United States should use nuclear weapons on their behalf. Even in circumstances where an ally approves of U.S. nuclear use, they should—if at all possible—get a say in how, when and where, and be given fair warning before it happens.
Regular deterrence dialogues established in the Obama administration serve an important function for assuring allies, consulting on U.S. nuclear weapons policy and signaling cohesion. However, the United States does not generally discuss hypothetical nuclear use scenarios in these dialogues for the simple reason that the officials conducting these dialogues cannot predict a president’s orders in a crisis. As a result, they do not provide allies with detailed information about when, why and how the United States could use a nuclear weapon to defend them.
Allies generally try to present a united front with the United States on extended deterrence issues, but sometimes public statements hint at deficiencies in alliance cohesion. For example, in response to a report of a plan that could include the use of 80 nuclear weapons against North Korea, a South Korean defense official recently told reporters, “I can say clearly that the use of a nuclear weapon does not exist in our [operational plans], and it is impossible to use military force without our agreement.” The sentiment, and the resistance to nuclear use, is widespread on the peninsula. Yet, while the United States may in practice need South Korea’s approval to conduct a protracted military campaign, there is no requirement for a U.S. president to consult with Seoul prior to nuclear use, let alone to secure its approval. South Korea does not have detailed knowledge of the full set of available U.S. nuclear employment options, which exist separately from the combined operational plan.
There is currently no requirement—or, in some cases, even an expectation—that the United States would consult with an ally prior to using nuclear weapons near its territory. Even worse, in some situations, there may not be a sufficient system available for timely consultation to occur.
NATO has an established process for member states to request a U.S. nuclear operation, including with the remaining U.S. weapons stored in Europe for NATO use. Since the 1960s, the alliance has recommended that “special weight” be given to consultation with allies on whose territory nuclear weapons may be used—but no member state has a veto over an employment decision and consultation would only take place “time and circumstances permitting.” The United States should ensure that effective procedures and systems are available to communicate with allied civilian and military leaders in all potential cases of nuclear use in Europe, including the smaller allies, and make it standard procedure for the president to exercise these mechanisms before ordering nuclear release.
In Asia, there are no established organizations or nuclear sharing arrangements to facilitate this kind of consultation. Allied officials often express frustration that bilateral deterrence dialogues are too general to help them plan for a crisis. An ally could request nuclear use at any time through channels established for conventional command-and-control systems or diplomatic coordination, but the allies likely would not be able to discuss specifics of nuclear operations in either setting, especially in wartime. On the other hand, allied leaders may never have an opportunity to weigh in against planned nuclear use near their borders.
If and when the United States reconsiders its procedure for how a U.S. president can order nuclear use, it should establish procedures and secure video, voice and data channels for the president to consult with the leadership of allied countries affected by the decision, including Australia, Japan and South Korea. The standing procedure for nuclear use authorization should have senior advisers prompt the president to consult with allies and to build in time for the conversation to occur—both in exercises and in a crisis. If an ally disapproves of a proposed nuclear operation, the president should seek other ways to accomplish the objectives of both parties.
Allied approval cannot be a formal requirement of the nuclear use authorization process. In some circumstances, it would be impossible or imprudent to consult with an ally before ordering a nuclear operation—for example, when a decision has to be made immediately, when consultation might imperil a mission, when it is impossible to establish a communications link safely and securely, or when the mission is unlikely to affect the ally’s territory or operations. But a U.S. president should make every effort to secure an allied leader’s agreement on a course of action in a nuclear crisis.
The act of setting up a procedure could be constructive in itself. U.S. allies have been deeply shaken by four years of an erratic president often dismissive of allies’ concerns, including by issuing careless nuclear threats in public that have surprised and alarmed allies. Even more than a bomber overflight or a port call from a ballistic missile submarine, discussing procedures for deliberation, establishing the communications channels and rehearsing these consultations can reassure allies that the United States takes its interests seriously. At the same time, U.S. officials should provide allied leadership with more detailed briefings about U.S. procedures, capabilities and plans in order to streamline consultation in a crisis and assuage any allied concerns about the shift in procedures. U.S. officials should discuss hypothetical nuclear employment scenarios with allies so that each partner can better understand the other’s interests. These briefings should put nuclear assurance discussions on a firmer footing than the current precarious edifice and provide an opportunity for U.S. officials to understand allied interests in different hypothetical contingencies. Furthermore, allies or adversaries may recognize these consultative procedures as enhancing the credibility of U.S. extended deterrence commitments as they could facilitate decision-making in a crisis and enhance alliance cohesion at the political, strategic and operational levels.
Establishing procedures for the president to consult with allies on nuclear use can lead to better operational planning, better alliance relations and a better informed decision. Just as the president should not make a decision on nuclear use without the benefit of counsel from domestic advisers, he or she should not make a decision without the counsel of foreign partners.
Requiring a Broader Certification on Legality
The sole constraint on a president’s nuclear employment order is that it must be consistent with international humanitarian law, commonly referred to as the law of armed conflict (LOAC). The current procedure for determining whether nuclear options comply with LOAC is opaque and too narrow to fully inform a presidential decision to employ nuclear weapons. As the administration reviews the procedures for authorizing nuclear use, it should also review how nuclear options are assessed relative to LOAC.
Each nuclear employment option, whether a preplanned option developed by U.S. Strategic Command (STRATCOM) in peacetime or an adaptive option developed during a crisis, must comport with at least three salient principles of LOAC: It must be necessary to attain a valid military objective that helps to end the conflict at hand (necessity), it must discriminate between military and civilian populations and minimize harm to the latter (distinction), and the collateral damage caused by the operation must be proportionate to its efficacy in ending the conflict (proportionality).
The United States fully accepts that LOAC applies to the use of nuclear weapons. As a matter of policy, the 2013 nuclear employment guidance stated that “all plans must also be consistent with the fundamental principles of the Law of Armed Conflict. Accordingly, plans will, for example, apply the principles of distinction and proportionality and seek to minimize collateral damage to civilian populations and civilian objects. The United States will not intentionally target civilian populations or civilian objects.” The 2018 Nuclear Posture Review pledges to “adhere to the law of armed conflict and the Uniform Code of Military Justice, and minimize civilian damage “to the extent possible consistent with achieving objectives.”
Joint Force doctrine establishes LOAC constraints over the nuclear planning process:
The law of war governs the use of nuclear weapons, just as it governs the use of conventional weapons. For example, nuclear weapons must be directed against military objectives. In addition, attacks using nuclear weapons must not be conducted when the expected incidental harm to civilians is excessive compared to the military advantage expected to be gained. U.S. policy on the use of nuclear weapons complies with all law of war requirements. [Combatant commanders], and other subordinate commanders responsible for the conduct of nuclear operations, must ensure their staff judge advocate is involved in nuclear operations planning and targeting processes.
Under the Uniform Code of Military Justice, military officers are obligated not to carry out an order that is inconsistent with the laws of war. In 2017, Gen. John Hyten, then head of STRATCOM and now deputy chairman of the Joint Chiefs of Staff, stated that he was prepared to inform the president when a selected option was illegal and would present the president with legally viable options. The same year, the former head of STRATCOM, Gen. Robert Kehler, said during a Senate hearing that he would have been willing to defy an unlawful order. STRATCOM staff assess and certify the legality of preplanned nuclear employment options as part of the planning process; a STRATCOM commander included in the nuclear planning conference would have to decide on the fly whether to raise LOAC objections to an adaptive option developed in a crisis. This obligation of combatant commanders to refuse unlawful orders is in practice a critical check on the president’s power.
Hyten said the process is “not that complicated,” but it contains a number of troubling ambiguities. In the hearing, Kehler admitted that an officer would be hard-pressed to refuse a commander in chief’s orders. If an officer refuses an order, this action may itself constitute a violation of the military code. Furthermore, the standards that military lawyers use to assess the legality of nuclear options remain unclear. Lastly, the duty not to comply with clearly illegal orders requires an implementing officer to make his or her own legal judgment as to whether nuclear use meets the law of war in that specific context.
The complex set of questions needed to make LOAC determinations are often highly subjective. By what standards do the judge advocates weigh the expected military advantages against the expected collateral damage? How do they assess an objective as militarily necessary? Would it be a valid military objective to order nuclear use to compel an adversary to relinquish conventional military gains when the United States and its allies face local overmatch? What about strengthening U.S. credibility for nuclear use in future crises—for example, enhancing peacetime deterrence? Under LOAC, the president should not be able to order an unprovoked nuclear operation, but what qualifies as an attack that could justify nuclear use? If an adversary uses nuclear weapons first, would a conventional response option be more proportionate to the military benefits attained, cause less collateral damage or be less likely to escalate a conflict? When do the radiation effects of a nuclear detonation contravene LOAC’s injunction against actions that cause cruelty or wanton violence?
How U.S. nuclear plans have interpreted the presumption against targeting civilians has evolved over time. During the Cold War, U.S. nuclear war plans included not only military targets in civilian areas but also a category of “population” targets. Because “countervalue targeting” is generally recognized as inconsistent with LOAC, in revising the joint doctrine for nuclear operations in 2003, STRATCOM proposed to rename “countervalue targeting” as “critical infrastructure targeting.” When other commands objected, the Joint Chiefs of Staff simply deleted the entire section.
There are no authoritative legal, ethical or empirical standards for answering these questions, requiring the United States to develop its own standards for assessing whether orders comport with LOAC obligations. Furthermore, the United States does not publicly discuss how it interprets these complex questions with respect to nuclear weapons, contributing to ambiguity for allies and public observers. For example, the process is not discussed in the Pentagon’s Nuclear Matters Handbook, which depicts the nuclear planning process as proceeding directly from “objectives and guidance” to “target development” to “expected damage assessments.”
Just as the military’s obligation to refuse unlawful orders is an important check on civilian leadership, the standards of LOAC are an important check on the planning process. The difficult interpretive questions that constrain STRATCOM planning should not be the sole purview of STRATCOM attorneys, and a decision to raise LOAC questions in a conference assessing a potential employment option against the context of a rapidly evolving crisis should not be left to the discretion of a combatant commander. The president and other civilian officials should help to determine the standards by which a nuclear employment order is assessed as legal under LOAC, ensure that the president’s orders in a crisis comply with LOAC in the first place, and identify and prevent the implementation of unlawful orders.
If and when the United States revises its nuclear authorization procedures as part of a new nuclear policy review, it should also review how determinations of legality are made and ensure the system is as rigorous as possible. The president, in consultation with military commands, should issue guidance about how to assess necessity, proportionality, discrimination and any other standards he or she considers necessary to comport with international and domestic legal commitments. A group consisting of the Department of Defense Office of General Counsel, the National Security Council legal adviser, the State Department legal adviser—known within the national security bureaucracy as the Interagency Lawyers’ Group—and the judge advocates of the relevant geographic and functional combatant commands should assess nuclear employment options relative to the president’s guidance.
This group will need to certify the legality of nuclear employment options in two contexts. First, representatives of these offices detailed to STRATCOM can assess preplanned options as they are developed. Second, these officials or, if necessary, their representatives, should be networked into the nuclear command-and-control system to rapidly assess and approve a presidential order during the president’s conference with senior advisers. Because determinations about proportionality, discrimination and necessity cannot be made without a complete understanding of the context of a crisis, this group would need to recertify approved preplanned orders at the time they are issued. Adaptive employment options, developed as a crisis is taking place, would need to be certified as consistent with the nation’s LOAC obligations in that context. If an administration decides to retain the option to launch nuclear forces in a matter of minutes on confirmation of a massive incoming nuclear attack, these preplanned options can be assessed in advance and, if necessary, approved immediately as a president issues the order to execute these plans. In each case, the group will need to consider the military’s expected damage assessments, available nonnuclear options, the course of the conflict and the nation’s political objectives as set out by the president.
The current system for authorizing employment of U.S. nuclear weapons deprives the president of critical information necessary to make a fully informed decision and is therefore insufficient to meet U.S. national interests. Because U.S. interests depend not only on speed and compliance of the military but also on alliance cohesion and U.S. standing as a nation in compliance with the law of armed conflict, the system for employing nuclear weapons should provide for consultation with allies and require a more robust system for certifying that employment options comport with the law of armed conflict. In the next nuclear policy review, the United States should adopt a more rigorous system that not only requires the concurrence of multiple officials but also ensures that the president’s decision is based on the best possible advice from allies and attorneys.