The Operational Consequences of Conflating the “Why” and “How” of War

In conflict, determining whose cause is “more just” can span the spectrum of opinion and complexity. For example, most States consider Ukraine to be the “victim” State in its international armed conflict (IAC) with Russia. Shortly after the invasion, the UN Security Council attempted, but failed, to pass a resolution condemning, in the strongest terms, Russia’s violation of Article 2(4) of the UN Charter. Predictably, Russia vetoed the resolution, which had otherwise garnered the support of eleven members.

Despite strong opposition, Vladimir Putin remains steadfast in his justification of Russia’s February 2022 invasion as a lawful, preemptive strike against Western aggression and necessary to protect Russia’s rightful imperial hold over Europe’s east. To Putin, the influence of the West is his existential threat which justifies executing violence against another State.

Meanwhile, Hamas continues to justify its initial attack and ongoing fighting as revenge for past Israeli attacks, the constant Israeli occupation of the West Bank, the arrest of Hamas leaders, isolation, and Israel’s past bombing of Gaza. In response, Israel cites self-defense and retribution as justification for their response to the horrific October 7, 2023, attacks. The two sides believe deeply in their cause and therefore, rely on it in their own respective reasoning for tactics used over the past year (see here and here).

The key question, therefore, is whether why we fight, even if that justification relies on a deeply held belief, is sufficient to change how we fight.

Scholars have long contemplated the distinction between jus ad bellum (the law that regulates resorting to force) and jus in bello (the law that governs conduct in war) (see here, here, and here). Of those scholars, some have further challenged whether this distinction is realistic in a world where the subjective reason for armed conflict inevitably impacts the way humans wage war. While there are practical challenges to cleanly separating the two bodies of law, any formal adjustment to existing jus in bello rules based on a belligerent’s cause would have dire operational consequences for the warfighter and their legal advisors.

By maintaining the current construct for the law that governs war, commanders will be better able to make decisions, create policy, and develop clear rules of engagement (ROE). Furthermore, commanders can only assess risk and hold those under their command accountable when they can rely on policy derived from unwavering rules. Finally, by conflating the regulation of the use of force with the law that governs conduct in war, belligerents risk engaging in conflicts that rapidly escalate into lawless fighting without a clear path to a peaceful resolution, placing noncombatants at the highest degree of risk.

The Argument for Conflation—“The Sliding Scale”

Arguments in favor of blurring the line between the two bodies of law tend to rely on the notion that it is wrong (and perhaps impossible) to assess rules for the conduct of war without giving some consideration to the type of war involved. In Just and Unjust Wars, Michael Walzer contemplates the argument that the jus in bello rules should be applied with a “sliding scale” reflective of what’s at stake in a particular conflict. In other words, the “greater the justice of my cause, the more rules I can violate for the sake of that cause” (p. 229).

But it is not only academics who wrestle with this question. The International Court of Justice (ICJ) Nuclear Weapons advisory opinion reflects a similar reluctance to adhere to clear separation. In its inconclusive holding, the Court could not definitively say whether “the threat or use of nuclear weapons would be lawful or unlawful in an extreme circumstance of self-defense, in which the very survival of a State would be at stake.” The Court recognized the challenge of strict adherence to such a separation in extreme cases of State survival.

In broad terms, the argument goes that when the law limits a nation’s ability to defend itself, perhaps strict adherence to international humanitarian law (IHL) is insufficient to prevail. Therefore, a nation fighting for its very existence should be afforded certain allowances for necessary deviations. The importance, however, of maintaining this dichotomy is nonetheless essential to the operational warfighter.

The Historical Dangers in Conflating the “Why” and “How”

In all armed conflict, there is an “aggressor” and a “victim.” While those labels are inherently subjective given that victimhood resides in the eye of the beholder, there is an objective, fundamental difference between a war of existence vice a war of convenience. And although the perceived “justness” of a belligerent’s cause has historically informed the decisions made in bello, doing so has resulted in grave and prolonged violence.

In defense of Great Britain, Winston Churchill characterized the June 1943 air campaign against the populous German industrial centers of the Ruhr as a “grim necessity of a just war” (p. 3). It was largely Mr. Churchill’s decision to flatten or burn one-fifth of German homes, render 7.5 million people homeless, and kill or wound one million German civilians. As the leader of an island nation whose very existence was at stake, Mr. Churchill faced a threat of invasion similar to present-day Taiwan.

At the time, only 42 States were parties to the 1929 Geneva Conventions (including Germany), compared to the 196 States party to today’s 1949 Conventions. Additionally, the specific law governing area bombing, a new technology at the time, remained unsettled. While some States attempted to ratify international instruments on the issue, they were incomplete; indeed, much of what guided Mr. Churchill’s difficult decision-making was not the “law of war,” but instead his own notions of morality (p. 12).

Despite the devasting impacts of aerial bombing, evidence suggests the campaign did not destroy the morale of the German populace. Instead, the use of the tactic solidified the resolve of the people, resulting in the opposite intended effect and prolonged violence.

As the first international armed conflict after the ratification of the 1949 Geneva Conventions, the Korean War offered the first glimpse at attempts (or lack thereof) to implement this newly developed law of war. The Third Geneva Convention (GC III) required new protections for prisoners of war (POW), specifically delineating rules for their treatment and release. While it’s true the United States did not ratify this Convention until 1955 (two years after the end of the war), all parties made a unilateral declaration pledging to abide by the terms of the Conventions. Nevertheless, subjective military and political interests overrode those pledges and, as a result, the treatment of POWs and civilian internees by all parties to the conflict fell woefully short of these new rules, prolonging the war and preventing an armistice.

Historical Compliance and its Consequences

As IHL continued to develop and become an integral part of warfighting, patterns of compliance began to emerge. The Vietnam War marked a change in the United States’ posture toward compliance with the law of war. Despite highly publicized war crimes such as those at My Lai and the politically polarizing nature of the war domestically, this conflict marked a change in U.S. policy toward not only complying with, but in fact extending IHL protections beyond what the law required. Article 4A of GC III, for example, establishes the categories of people who, having “fallen into the power of the enemy,” qualify for prisoner of war status. As an unaffiliated guerilla force, the Viet Cong fell outside these protected categories. Regardless, the United States made the strategic decision to treat both North Vietnamese and Viet Cong detainees as POWs.

Fast forward to the 1990s, during Operation Desert Shield and Desert Storm, the coalition coupled its relentless air campaign against Iraq with leaflets and loudspeaker announcements indicating that Iraqis would be treated humanely if they surrendered. As a result, Iraqi soldiers surrendered in droves, expecting that coalition forces would treat them fairly and humanely. Within 100 hours, 80,000 Iraqi soldiers either surrendered or were captured. Despite the incredibly large number of troops involved, there were no reported or known instances of prisoner maltreatment (p. 81).

A belligerent’s justification for conflict will inherently color events and influence decisions. While history reflects this reality, it also suggests that when adhered to, an unaltered law of war (jus in bello) perhaps provides our best hope to end hostilities.

The Challenges of Operationalizing a Blurred-Line Approach

Because future battlefields promise to be more complex, inviting further, or even formal, conflation of the jus ad bellum and jus in bello rules is not only strategically dangerous but operationally untenable. Development of domestic policy, ROE, and tactical training are all anchored in the law and principles of IHL. For all three to be developed consistently, the law that governs conduct in war must remain unchanged despite each party’s subjective belief as to cause. Joint U.S. doctrine defines ROE as: “[d]irectives issued by competent military authority that delineate the circumstances and limitations under which United States forces will initiate and/or continue combat engagement with other forces encountered” (Joint Publication 3-84, p. GL-3).

While ROE are not legal rules, they are binding policies derived from both IHL and national policy objectives. For U.S. forces, ROE are conflict-specific and developed with critical input from military legal advisors (JP 3-84, p. III-2). By replacing bodies of law with a “sliding scale” based on circumstance, those who develop, train, and employ conflict-specific ROE would be forced to use inconsistent legal rules as the basis for critical war fighting policy. This strategic inconsistency could lead to a “patchwork” application of IHL at the tactical level, potentially prolonging hostilities and ultimately failing to achieve strategic ends.

Furthermore, a military commander fills several important roles that are reliant on unwavering rules. One of the most critical responsibilities of a commander is to assess relevant risks and make decisions based on that assessment. Grounding that determination in steadfast rules allows commanders (and their legal advisors) to accurately assess risk. Commanders also hold the critical weight of command responsibility. Article 87 of Additional Protocol (AP) I requires military commanders and others under their command and control to prevent and report breaches of IHL. While the United States has not ratified AP I, § 18.4 of the Department of Defense Law of War Manual reflects a similar requirement, obligating commanders to implement and enforce the law of war. This includes preventing and reporting violations as well as holding accountable those who commit violations. Accountability is only possible, however, if the metric by which a violation is judged remains unchanged despite subjective justification.

Finally, in bello rules altered by individual justifications for violence cuts against the very purpose for which IHL exists: to protect populations impacted by armed conflict and bring an end to hostilities as quickly as possible. Conflicts governed by shifting rules could become more, not less, escalatory, prolonging violence and the harm inflicted on civilians. Public trust in the actions of belligerents is contingent on the sincere belief that those who engage in violence will follow the same set of rules. For individuals whose lives and livelihoods are literally caught in the crossfire, IHL is critical to their safety and for maintaining humanity in war. Should the rules flex, conflicts will resemble the characteristics of total war envisioned by Clausewitz, becoming more violent and escalatory.

The Future of Conflict

Similar to Winston Churchill’s struggle with the decision to employ tactics not yet contemplated by the law, the future of warfare will present challenging questions when it comes to domains and technologies, including questions the law has not fully answered. Indeed, we find ourselves in an era of emerging and disruptive technologies being used in conflicts of existential importance. As a result, some nations may be tempted to suspend, or at the very least temper, their adherence to IHL.

The rapid evolution of cyber warfare, advanced manufacturing, biopharmaceuticals, machine learning, and drone capabilities are just some of the arenas where gaps in IHL are at risk of exploitation by belligerents looking to achieve their subjective ends. The struggle to apply IHL to developing tactics has already played out in current conflicts, with civilian hacktivism, the use of civilian apps to assist in military targeting, and the increasing involvement of the private sector in warfare. Faithful adherence to the in bello rules, unchanged by our ad bellum reasoning, will guide commanders and their legal advisors to reach the most legally sound decision. The warfighter’s ability to make the right choice in the absence of a pointed rule is contingent on these anchoring and distinct standards.

The authors would like to thank Dr. Nick Roland, Regimental Historian, U.S. Army JAG Corps, for his invaluable contribution to the historical examples referenced in this post.

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Photo credit: U.S. Army, Spc. Kelsey Kollar