In recent remarks to graduates at the National Defense University, the Chairman of the Joint Chiefs of Staff, General Dan Caine drew a sharp distinction between two categories of advice in military operations: “can we do this?” versus “should we do this?” He stated that the first category is appropriate for military leaders to address, but that the second is verboten, suggesting it would be a breach of professional norms (at least) or subversion of civilian authority (at worst).
This is an important distinction, and there are clearly certain issues that fall into one category or the other. For example, it should be indisputable that ultimate policy decisions (e.g., whether to start, join, or exit a war, and what the nation’s strategic goals shall be by engaging in hostilities) are best left to civilian leaders, and therefore outside the military’s scope of responsibility. They fit in the “should we do this?” and, as Caine said, “we don’t do that in our business.” But the two categories can benefit from more analysis, and, indeed, I suggest there are some “should we” questions that military leaders are equipped to and should help answer.
In this essay, I use the Chairman’s classification as a launching off point. I explain, in detail, why legal advice fits squarely within the first category. Indeed, legal advice is the routine business and the professional obligation of military leaders to consider and legal constraints help directly answer the “can we” question.
As I explain, whether a military campaign, mission, or operation is lawful is completely within the purview of military officers, a textbook example of a consideration in the “can we do this?” analysis before the civilian official is responsible for deciding whether we should or should not do this. With the United States entrenched in one legally-dubious international armed conflict against Iran and engaging in a patently unlawful campaign against drug cartels, it is an important time to underscore the role of the military leader in that set of questions and to map the full sources of authority and precedents for it.
In this essay, I also suggest there are some aspects of the “should we” question that military leaders can address. It is admittedly debatable (in contrast to the legal “can we” question, which is not) what scope of advice fits within the military’s responsibilities in this second category. I show why there is a circumscribed but important set of “should we” questions that military leaders are equipped to help civilian leaders address.
Well-Settled, Best Practices
In late 2017, when tensions between North Korea and the United States were spiking, the world was witness to unusual sabre-rattling threats by President Donald Trump. U.S. Air Force General John Hyten, who was then the commander of U.S. Strategic Command responsible for the country’s nuclear arsenal, was questioned by reporters at the Halifax International Security Forum in Nova Scotia, Canada about what would happen if he were ordered by the president to launch a nuclear strike on North Korea. Why he said what he did is as important as what he said.
I provide advice to the President. He’ll tell me what to do, and if it’s illegal, guess what’s going to happen? I’m gonna say, “Mr. President, that’s illegal.” Guess what he’s going to do? He’s going to say, “What would be legal?” And we’ll come up with options of a mix of capabilities to respond to whatever the situation is, and that’s the way it works. It’s not that complicated.
General Hyten was correct to imply that he would push back on an illegal order, and that this duty is not all that “complicated.”
Fast forward to March of 2026. The commanding officer of U.S. Northern Command, Gen. Gregory Guillot, was asked by Senator Jack Reed (D-RI), Ranking Member of the Senate Armed Services Committee, about the law banning troops from polling sites. His answer: “I am aware of the code, and I recognize that it is against the law, and I would not follow an unlawful order.” Gen. Guillot’s statement of the law (and he’s not a lawyer) would be correct: troops are prohibited from being at polling sites unless there to “repel armed enemies of the United States” by 10 U.S.C. § 592. So was he correct about the need for him to “recognize” that legal prohibition and that he may not follow an order to violate it.
The Defense Department’s “Decaying Legal Culture”
Missy Ryan and Nancy Youssef of The Atlantic recently wrote a startling piece about the extension of the norms of proper military subordination to civilian government – norms best expressed by the late Samuel Huntington in his seminal work on civil-military relations: The Soldier and the State (“politics … is beyond the scope of military competence”). What raises the stakes about this set of issues is the backdrop of apparently unlawful actions by the U.S. military and concerns about outsourcing sure-to-be-controversial legal assessments to non-experts at the Department of Justice’s Office of Legal Counsel, led by apparent political loyalists.
The context of ongoing military actions and what Jack Goldsmith has called the Department of Defense’s “decaying legal culture” is important. First, the near year-long campaign to kill “narcoterrorists” in the Caribbean and eastern Pacific is plainly illegal under both domestic and international law. Second, Secretary Pete Hegseth’s flippant regard for the laws of war in general, his unseemly “contempt” for JAG officers, his fixation on “maximum lethality, not tepid legality,” and – because they might be “roadblocks” to the Trump administration’s unprecedented use of the military – the Secretary’s replacement of the senior JAG officers of the Army and Air Force with less-experienced national guard JAG general officers in defiance of historical practice and the statutes establishing the process for selecting these high-ranking legal officials. Third, both Hegseth’s and Trump’s repeated rhetoric meant as genuine threats to Iranian leaders – and the civilian population – raise obvious potential for war crimes. If the U.S. military executed its missions to the letter of Trump’s public commentary, American troops would be committing grave breaches of the Geneva Conventions and Hague Conventions, and could be prosecuted by international tribunals or even by court-martial or in a federal district court in a future U.S. administration seeking accountability for wrongdoing.
Add to this that the commanding officer of U.S. Southern Command reportedly decided to retire early when his objections to the boat strikes in his area of responsibility went unheeded. If accurate, that decision would appear consistent with guidance that Gen. Caine’s legal counsel reportedly provided, which was for a military commander to request to retire if they determined they received an unlawful order. (Whether a senior officer should subsequently explain in public her reasons for resignation or retirement is a separate and difficult question.)
These problems should help us sharpen our thinking about who has responsibility for addressing the “can we” and “should we” questions and the proper scope of those questions.
“Can we?” includes legal constraints
The law, Department of Defense regulations implementing that law, military doctrine, and historical precedent all suggest the “can we do this?” question cannot and must not simply mean “will this work or not?”
The law demands its own observance
Consider first the federal law that imposes certain duties on the Chairman of the Joint Chiefs of Staff (CJCS) and the four-star combatant commanders that are explicit in their demand that these leaders act in accordance with laws relevant to the use of military force. First, one of the CJCS’ core duties is “providing advice to the President and the Secretary on ongoing military operations” (10 U.S.C. § 153(a)(3)(A)). In aid of that duty, the CJCS has his own office of legal counsel, led by a JAG general or admiral who is statutorily required to give “independent legal advice” to the CJCS on issues within the scope of his responsibilities.
As for those four-star combatant commanders reporting directly to the Secretary of Defense and the President, they each give “authoritative direction” over military operations and conduct of tens of thousands of subordinate uniformed personnel and civilian employees. Laced into their duties, 10 U.S.C. § 164(c)(1)(F) establishes that one of their statutory responsibilities is “coordinating and approving those aspects of administration and support (including control of resources and equipment, internal organization, and training) and discipline necessary to carry out missions assigned to the command.” An obvious and necessary component of carrying out missions with appropriate “discipline” is the adherence to legal constraints on the exercise of military power – primarily drawn from the Geneva and Hague Conventions and described in detail in the Department of Defense’s own Law of War Manual. (Indeed, the DoD has for decades resisted other relevant departments or agencies, like the Departments of Justice and State, having a greater role in interpreting its law of war obligations; the Manual itself has been criticized for not reflecting an official government-wide interpretation of this law.) As is the case with the CJCS, each combatant commander is advised by a joint staff of planners and experts, including senior uniformed legal advisors (the “staff judge advocate”). Federal law also prohibits anyone in the Department of Defense – uniformed or civilian – from interfering with the “independent legal advice” these officers provide to the commanders.
Then there is the federal statute that imposes four additional duties bound together as the “requirement of exemplary conduct” for all “commanders and others in authority.” 10 U.S.C. § 7233 (applicable to the Army, but identical statutes impose requirements on the Navy/Marine Corps and Air Force/Space Force) states that these uniformed leaders are:
required to show in themselves a good example of virtue, honor, patriotism, and subordination; to be vigilant in inspecting the conduct of all persons who are placed under their command; to guard against and suppress all dissolute and immoral practices, and to correct, according to the laws and regulations of the [Armed Service], all persons who are guilty of them; and to take all necessary and proper measures, under the laws, regulations, and customs of the [Armed Service], to promote and safeguard the morale, the physical well-being, and the general welfare of the officers and enlisted persons under their command or charge. (emphasis added)
To be sure, these normative duties explicitly demand that the law remains front and center of all leaders’ operational decision-making and – by implication – the advice that the most senior ranking officers give to senior civilian officials with the power to command and control military force.
Then there is the UCMJ, which punishes conduct that is in “dereliction of duty,” is “unbecoming an officer,” and “of a nature to bring discredit upon the armed forces.” Acting unlawfully, or even being silently complicit to the use of force they should reasonably, know to be unlawful, would all be chargeable offenses under the UCMJ, a code of martial expectations, norms, and dictates with which these senior officers are well-accustomed.
Department of Defense rules and regulations
Next consider the Department of Defense regulation that commands respect for and adherence to the laws of armed conflict, DoD Directive 2311.01, the “Law of War Program.” Para. 1.2 states clearly:
Members of the DoD Components comply with the law of war during all armed conflicts, however characterized. In all other military operations, members of the DoD Components will continue to act consistent with the law of war’s fundamental principles and rules, which include those in Common Article 3 of the 1949 Geneva Conventions and the principles of military necessity, humanity, distinction, proportionality, and honor. … The law of war obligations of the United States are observed and enforced by the DoD Components. (emphasis added)
Compliance with law is, therefore, a relevant and essential factor in the design of all plans and the execution of those plans. This policy goes on to establish requirements “to prevent violations of the law of war” that most certainly would draw the attention of military planners and commanders as they consider their tactical, operational, and strategic options in the use of military force abroad. These requirements include:
(1) Law of war dissemination and periodic training. (2) Qualified legal advisers advising on the law of war. (3) Instructions, regulations, and procedures to implement law of war standards and establish processes for ensuring compliance.
Moreover, the Department’s leaders must develop appropriate and adequate measures for investigating noncompliance and holding accountable those who violate these laws. These measures include:
(a) Providing additional training. (b) Taking adverse or corrective administrative action, including non-judicial punishment. (c) Instituting criminal proceedings. (d) Revising or issuing policies, regulations, instructions, procedures, training documents, or other guidance to incorporate lessons learned.
Military Doctrine
Next consider military doctrine. Joint Publication 3-0 (“Operations”) states: “National strategic direction is governed by the Constitution, federal law, United States Government policy, internationally recognized law, and the national interest as represented by national security policy.” It also states: “All such DOD operations and activities shall be consistent with US domestic law and international law.” Joint Publication 5-0 (“Planning”) states that commanders “must also anticipate and incorporate planning factors such as domestic and international laws, regulations, and operational limitations on the use of contributed forces, various weapons, and tactics.” It includes “laws and authorities” within the bucket of “operational limitations” and discusses them as relevant “constraints” and “restraints” that military planners must take into account. Joint Publication 3-84 (“Legal Support”) further describes the critical and required role for military lawyers advising their commanders on the implications and demands of international law and domestic law (including the Constitution and criminal law) on military operations, both proposed and ongoing. Every Chairman is ultimately responsible for the content, publication, and dissemination of these Joint Doctrines – a requirement imposed by 10 U.S.C. § 153(a)(6).
“Should we?” as a question the generals can, in part, answer
All that said, a reason to be concerned about the distinction between “can we?” and “should we?” is that it risks excluding the senior military leader from the latter altogether. But there is space for “should we” within the role of the senior military leader, if it is properly scoped. Properly scoped includes adherence to a cardinal principle that senior military officers should not undermine a president’s policy choices or substitute their policy preferences for a president’s. In contrast, federal law, historical practice by former senior military leaders, and the Defense Department’s own “Joint Doctrine,” which the Chairman publishes, all demand that senior military officers have in the foreground of their work the strategic picture, not just tactical effectiveness of air strikes, the logistics of moving aircraft carriers between theaters, or the rate that munition stockpiles are being used.
Congress assigns senior military leaders such responsibilities by statute (like 10 U.S.C. § 164(b)(3), establishing “primary duties” of the combatant commander; and 10 U.S.C. § 153, establishing the myriad “functions” of the CJCS). As Morris Janowtiz, a well-regarded military sociologist and contemporary of Huntington, once wrote: “while every military task ultimately impinges on international politics, some senior officers have tasks which involves direct political planning and political negotiation” and “are thoroughly enmeshed in the political estimates as they prepare their strategic plans.” These statutes illustrate Janowitz’s description that the civil and military contexts are “fused” at this high level of national security administration.
Moreover, excluding military leaders from “should we” considerations does little to support basic constitutional subordination of the military to civilian government. According to civil-military relations scholars like Risa Brooks, a cramped view of the military officer’s lane of professional expertise and judgment espoused by Huntington ignores the risk that military deference to certain political choices may encourage a public perception of the military as a partisan arm of presidential policy-making. This in turn can corrode the public’s trust in the military’s fidelity to the Constitution over fidelity to certain officeholders and can induce the military (or individual military leaders) to actually behave with partisan motivations to advance partisan outcomes.
Additionally, Brooks warns that the “reflexive self-identification of military officers as apolitical can encourage blind spots such that they fail to recognize the political content or impact of their actions.” Merely focusing on the technical ability to conduct air campaigns against drug traffickers in the Caribbean, for example, would miss the larger picture: the President has reclassified without precedent these criminal threats into military targets to leverage the far more permissive law of war and to demonstrate aggressive commitment to a policy agenda. And doing so has triggered intense congressional skepticism and well-grounded accusations of murder, questionable results, polarized public support, and damaged relationships with military allies and intelligence community partners. Whether that ought to continue is not beyond the moral and professional reasoning of a senior military leader. As even Carl von Clausewitz wrote, “no major proposal for war can be worked out in ignorance of political factors,” a sentiment that leading civil-military scholars like Brooks, Janowitz, Peter Feaver, and Lindsay Cohn have long recognized.
An overly narrow vision of what these senior officers must consider when advising their civilian principals also does not match historical reality. Professor Eliot Cohen described some of the most successful wartime relationships between presidents and their generals as a “dialogue of unequals” reflecting, on one hand, the legal subordination of the military but, on the other hand, the recognition that the civilian official is “always haunted by his own lack of experience at high command.” Far from simply taking orders as they come without giving input and offering debate, the senior officer can shape – but not dictate – the ultimate decisions made by their civilian principals. In this vein, retired General Martin Dempsey, Chairman from 2011-2015, said “[a]ll of my predecessors … when they came to educate me about my job, the single consistent, persistent theme was candor … relationships based on candor.” But even more specifically, he noted a few years earlier in an official Army white paper on the “profession of arms” that:
[m]ilitary professionals hold unique expertise and their input is vital to formulating and executing effective policy. This requires that the military’s unique perspective and advice be heard in the formulation of laws and policies that create, support, and employ our armed forces, or its effectiveness can be reduced to the detriment of the Republic.
That description of a broad perspective – informed by their education, experience, and professional judgment – is surely not confined to the “can we” question.
Consider also the views of Retired Lieutenant General James Dubik, a rare general officer with a Ph.D. in philosophy, who has criticized many of the modern assumptions underlying American civil-military relations, but notably wrote that “both civilian and military leaders have a duty to provide their best advice, make their best case, challenge assumptions and predictions, and present evidence and counterevidence as the debate ebbs and flows.” When that happens, he says, “good war-waging decisions are most likely to emerge from [this] set of political and military leaders bluntly and continuously arguing with one another.”
Finally, it is well worth remembering President John F. Kennedy’s admonition to his senior generals and admirals on the Joint Chiefs of Staff – those he believed had failed to live up to their responsibilities as expert advisors to the civilian decision-maker leading to the disastrous and failed Bay of Pigs invasion in 1961:
I expect the Joint Chiefs of Staff to present the military viewpoint in governmental councils in such a way as to assure that the military factors are clearly understood before decisions are reached. … [and] [w]hile I look to the Chiefs to present the military factor without reserve or hesitation, I regard them to be more than military men and expect their help in fitting military requirements into the over-all context of any situation, recognizing that the most difficult problem in Government is to combine all assets in a unified, effective pattern.
That then returns us to the proper sequencing and content of the “can we” and “should we” questions. One cannot, and should not, read the law, DoD regulations, or military doctrine as suggesting that compliance with domestic and international law does not act as a constant constraint on military operations or that legal consequences are not legitimate elements of the “should we?” question. Rather, the law is a necessary part of the “military viewpoint” or a “military requirement” expected to be assessed by military leaders from the CJCS and others on down. The law is, and has been for a very long time, an imperative consideration in the planning and execution of all military operations from the mundane to the controversial. In this way, the dictates of the law are most definitely part of the “can we?” bucket of military advice as surely as are the dictates of ordnance depletion and whether the right unit for a particular mission is a special operations force or a conventional air wing.
The follow-up “but should we?” question – one for which the military leader can propose an answer but for which the civilian national command authority must ultimately be accountable – also factors law in the overall risk assessment. But that assessment is of course contingent on what the law says in the first place. “We might go to jail for this” is a legal consequence of conduct that risks violating the law, obviously, and that consequence is a relevant factor in whether to risk engaging in potentially unlawful conduct at all. It is on the shoulders of these senior uniformed leaders to explain why and how the proposed action is lawful or unlawful in the first place – and that requires understanding the law as a set of constraints on what is even possible to do with military force.
Conclusion
Whether a particular use of military force is legal or not is a fundamental question that all military commanders must address when considering, planning, and executing operations. Moreover, the “law” is best considered a relevant “constraint” or “restraint” on operational planning, as any commander and any JAG officer can readily attest, according to the military’s own Joint Doctrine. The statements by Generals Hyten and Guillot, quoted earlier, demonstrate how a senior military commander can correctly view their mission within constraining legal frameworks – they represent what right looks like. In August of 2020, then-CJCS Gen. Mark Milley told Congress that he was well aware of the law keeping the military out of elections and election disputes, expressly stating he “will not follow an unlawful order” that would facilitate such a use of military force despite indications from President Trump at the time that such a plan was not out of the question. Milley too demonstrates the wide range of considerations for which it is entirely proper – and expected – for the CJCS or a combatant commander to weigh.
It is beyond any dispute that the law is in the “can we” part of the equation for military leaders. Whereas reasonable minds may disagree over the proper allocation of responsibilities for the “should we” inquiry. To the extent that any commander believes that law is exclusively a part of the civilian’s “should we?” calculus, not their own operational analysis of what is possible, they are mistaken. What’s more, military doctrine and regulations, federal law, and past practice all show that what fills in both the “can we?” and “should we” buckets is infused with legal limits and legal consequences. These considerations of what is possible for the military to do, and what ought to be done given those constraints, necessarily include legal facts and legal analysis by those with the deepest and most directly relevant experience and expertise. Thinking otherwise is what can lead to more than two hundred people (so far) purposely killed by military strikes without the due process of law and without the authority of the President to lawfully command it.
