Reexamining the Law of War for Great Power Competition

by , | Jan 27, 2021

Great Power Competition. Army’s XM1299 extended-range-artillery-cannon. Army photo by Lance Cpl. Katherine Cottingham


The United States has shifted its national defense posture to focus on “the reemergence of long-term, strategic competition” with “revisionist powers”—namely China and Russia. The government is heavily engaged in framing the assumptions and expectations of what is being called “Great Power Competition” (see, for example, here and here). This is, obviously, a significant shift for the United States after twenty years focused on fighting transnational, ideologically motivated non-State armed groups.

For the Biden Administration, and particularly for those returning to government service with previous experience in counterterrorism and counterinsurgency, preparing for a potential conflict with peer adversaries may be jarring. This post briefly highlights broader law of armed conflict implications of Great Power Competition to inform the ongoing efforts to reorient our defense and security posture.

Reaffirm the Line Between Policy and Law

Great Power Competition, while difficult to define precisely, refers broadly to military, political, and economic competition between peer or near-peer States. In the armed conflict context, it envisions adversaries with comparable resources (such as aircraft, artillery, and other weaponry) and reach. The shift is significant for the United States. We have grown accustomed to fighting asymmetric wars against groups with limited resources or military power (see, for example, here and here). In fact, post-9/11 armed conflicts often required the United States to restrain its overwhelming advantages in means and methods through policy limitations much stricter than those required under the law of armed conflict.

In an armed conflict against a Great Power, the United States would not be afforded such a luxury. The risks of defeat would be much higher and the consequences of losing catastrophic. Accordingly, the United States. must reexamine existing policy restrictions and the paradigm used to understand and implement obligations under the law of armed conflict.

This may be difficult as the nature of post-9/11 conflicts has afforded policymakers and commanders opportunities to focus on civilian casualty mitigation. For example, counterinsurgency doctrine in Afghanistan included directives intended to minimize risk to the local population by, among other measures, severely restricting use of air-to-ground munitions and indirect fires. Similarly, in 2013, President Obama issued policies demanding “near certainty” in targeting operations aimed at ensuring civilians would not be injured or killed. President Trump reportedly altered the 2013 rules in a still classified document. In contrast to these policies, the law of armed conflict recognizes that the humanitarian aim of reducing civilian casualties must be balanced with military necessity and so provides more leeway.

It is of course true that these policy measures were specifically designed for a particular operational environment, namely one in which the enemy takes advantage of legal requirements and hides within civilian populations. Nonetheless, as DoD considers armed conflict scenarios in the context of Great Power Competition, special care must be taken to ensure that these policy considerations do not creep into legal discussions. In other words, military leaders must ensure that civilian leadership fully understands what the law of armed conflict prohibits and what it does not during armed conflict and further that it does not equate previous policy restrictions to the outer bounds of the law of armed conflict.

Indeed, implementing counter-insurgency doctrine or maintaining a “near certainty” policy standard in targeting operations would be virtually unworkable in practice during an armed conflict with a Great Power adversary. It is obvious that the informational advantages enjoyed by the United States and coalition partners in armed conflicts against non-State actors would not be present in an international armed conflict against an opponent such as China or Russia. Technological developments are increasingly fortifying States’ anti-access/area denial systems, which will make it harder for belligerent parties to penetrate defensive bubbles. This will contribute to informational gaps on the battlefield, which will result in increased ambiguity.

It is thus important that U.S. officials understand and reaffirm the line between legal and policy restraints. In an environment in which anti-access/area denial systems are pervasive, officials must be prepared to abandon the policies of a foregone era and advocate and apply the less restrictive rules contained in the law of armed conflict (see, for example, paragraphs 2-29 and 1-44 of the U.S. Army’s law of war handbook).

Understand When the Law of Armed Conflict Applies to States

The shift in focus to Great Power Competition may tempt policymakers to imagine future armed conflicts that are akin to the global wars of the past, in which large formations of State armed forces engage in pitched battle on open terrain apart from populated areas. While this situation must be considered, policymakers must also recognize that States will continue to engage in what may be called “grey zone” conflict, including hostile cyber activity, political and economic subversion, covert action, and proxy warfare. In fact, in the context of Great Power Competition, strategic and political factors will incentivize engaging in grey zone conflict in lieu of transparent military engagements.

The ever-increasing competition among Great Powers in grey zones will cause difficulties in knowing when the law of armed conflict applies. As States increasingly compete and fight in obscurity to avoid legal consequences, it will become more and more challenging to recognize when the law of armed conflict threshold has been crossed. A good example is proxy warfare, in which States intentionally obscure their involvement to make attribution difficult. This, in turn, allows these States to avoid international legal consequences. Indeed, the future has already arrived as it is well documented, for instance, that Russia regularly uses the Wagner Group, an armed paramilitary organization, to hide (or at least deny) its involvement in areas of conflict like Ukraine, Syria, and parts of Africa. Additionally, the growing use of developing forms of warfare, such as cyber conflict and electronic warfare, will similarly place pressure on traditional interpretations of the law of armed conflict.

While these challenges have been present in ongoing conflicts, they will be heightened in Great Power Competition. As already noted, political, strategic, and legal calculations will make grey zone conflict appealing to States. Given the size and power of Great Powers, the stakes will be higher in such conflicts. This will generate complicated issues for Biden Administration officials. In some situations, calculations may well warrant maintaining the flexibility afforded by the legal ambiguity highlighted here, including both when and how the law of armed conflict applies to grey zone scenarios. Such calculations may have been at play when in 2018 United States armed forces actively engaged with irregular Russian forces in Syria. Nonetheless, officials must recognize the pressure such scenarios place on the legal regime and understand when it is appropriate to apply the law of armed conflict.

Embrace Technology’s Impact on the Law

DoD is focused on developing the means and methods of warfare that will enable U.S. armed forces to succeed on the future battlefield. For example, U.S. Army Futures Command—in line with the U.S. Army’s modernization effort—aims by 2023 to develop hypersonic missiles that can travel over 3,800 miles per hour, permitting the Army to strike anywhere in the world within minutes. Additionally, DoD is moving forward in development and implementation of artificial intelligence solutions to operational challenges.

These technological breakthroughs promise to increase the speed, and likely the scale, of lethality. Implementing the law of armed conflict in this environment will require careful consideration of both its humanitarian aims and operational effectiveness. The commander’s obligation to take feasible precautions in planning and conducting attacks to reduce the risk of collateral damage in these new environments (see AP I, art 57(2)(a)(ii) and DoD Law of War Manual, section 5.11) illustrates this challenge. New, advanced weapons, as well as the integration of machine learning technology into existing technology, will force developers and operational planners to give close thought to the balance between human and automated decision making in military operations. Of course, it must be kept in mind that only “feasible” precautions are required. This does not require warfighters to do everything possible—in an absolute sense—to reduce collateral damage. Rather, the analysis permits consideration of all circumstances ruling at the time, including humanitarian and military considerations (see paragraph of the DoD Law of War Manual). Even so, it seems inevitable that technological development will impact the way planners and operators evaluate the legal requirement to take precautions in attack.

The increased pace of technological development is likely to impact all areas of the law of armed conflict. For example, due to the speed of new battlefield technologies such as AI and machine learning, careful thought must be given to the role of the commander, the legal doctrine of command responsibility, and the ways in which law of armed conflict violations are investigated, including measures of accountability. The point here is to emphasize that policymakers must have a firm understanding of the law of armed conflict and, if necessary, be prepared to advocate for necessary changes.

Concluding Thoughts

The considerations outlined in this post are not exhaustive but are only intended to reveal the specter of future conflicts that involve devastating uses of force between enormously powerful adversaries. Policymakers must not shy away from the implications of such conflicts. Instead, they must recognize the potential for death and destruction unseen in recent U.S. armed conflicts. To do so requires bold leadership and sound judgment about how the United States marshals its armed forces in the context of Great Power Competition. But it also requires reasoned reflection on the ways in which the law of armed conflict permits and restricts battlefield conduct. This reflection must account for both humanitarian considerations as well as considerations of military necessity.


COL Shane Reeves is Professor, Head of the Department of Law, Co-Director of the Lieber Institute for Law and Land Warfare at the United States Military Academy at West Point, and Co-Editor-in-Chief of Articles of War.

Robert Lawless is an Assistant Professor in the Department of Law and Managing Director of the Lieber Institute for Law & Land Warfare at the United States Military Academy, West Point.