“Great Power Competition” Between Russia and Ukraine: Law of Armed Conflict Implications


| Jan 19, 2022

Ukraine Tank

In a previous article, we discussed the law-of-war implications arising from what the United States is calling “Great Power Competition” (for example, see here and here). Current events involving Ukraine are a concrete example of such competition and offer an opportunity to expand on our previous analysis. This post clarifies the challenges of regulating “Great Power Competition” while, simultaneously, reminding States of their obligation to comply with the law of armed conflict whatever the character of conflict.

Recent Russian Military Operations Against Ukraine

Over the last few months, Russia has alarmed the United States and its allies by amassing over 100,000 troops along its border with Ukraine. Russian President Vladimir Putin, blaming the West for the rising tensions, recently stated he would consider a military response to any NATO “aggression” in the context of Ukraine. To understand fully the implications of Russia’s current troop buildup, it is important to consider the history between these two States. Tension between Russia and Ukraine dates back hundreds of years. In recent decades, Ukraine’s cooperation and alignment with NATO and NATO member States (see here) has been a constant source of friction with Russia. It is through the lens of NATO-Ukraine cooperation that Russia observed 2004 and 2005 anti-government protests in Ukraine, known as the “Orange Revolution.” The protests sparked deep concerns in Russia and contributed to rising hostility between the two States. More recently, a series of perceived provocations, beginning in 2014, prompted Russia to deploy forces designed specifically to undermine Ukraine’s democratic government.

In February of that year, Ukrainian President Yanukovych fled following massive protests over his pro-Russian positions and heavy-handed response to democratic demands. Due to the strategic and historic importance of Ukraine to Russia, Yanukovych’s departure and replacement with a Western-friendly government was untenable for President Putin. Russia quickly counteracted with “a combination of Russian regular forces and unidentified operatives” to occupy “the recognized territory of Ukraine on the Crimean Peninsula.” Despite drawing fierce international condemnation, including from then-United States Secretary of State John Kerry—who called the invasion a blatant violation of international law—Russia annexed Crimea in March 2014. This occupation, which is ongoing, activated the law of armed conflict between Russia and Ukraine.

Almost simultaneously with its occupation of Crimea, Russia supported separatist militias in the Donetsk and Luhansk regions of eastern Ukraine. The militias’ access to sophisticated weapons, coupled with reports of Russian soldiers directly participating in the conflict, led NATO Supreme Allied Commander General Philip Breedlove to state “Russia is playing a leading role in the activities of the armed separatist groups in eastern Ukraine.” Russia denied participating in the conflict but did not refute claims “that up to 4,000 Russians, including active-duty soldiers currently on leave, had been fighting against Ukrainian government forces.” Since 2014, the non-international armed conflict between Ukraine and separatist militias in eastern Ukraine has continued almost unabated. The UN Office of the High Commissioner for Human Rights reports that violence has resulted in more than 13,000 deaths and more than 30,000 wounded.

Russia’s hostility toward Ukraine—whether the ongoing occupation of Crimea, the violent insurgency in the Donetsk region, or the most recent troop build-up—indicates a willingness to make threats or use force to further strategic interests. Russia’s behavior clearly implicates both the jus in bello (also known as the law of armed conflict) and the jus ad bellum strands of the law of war. More broadly, the conflict offers an opportunity to explore the international legal implications of a Great Power Competition.

It is worth noting further that, while Russia’s behavior most obviously relates to the parallel armed conflicts noted above—the belligerent occupation by Russia of Ukraine and the non-international armed conflict between Ukraine and Russian-backed separatists—these developments have important broader implications for other States involved in Great Power Competition. Tension between Russia and Ukraine has always garnered close attention from other powers, such as the United States and the United Kingdom. Russia’s recent troop deployments on the Ukrainian border are no less alarming to these States. Accordingly, while the discussion that follows is situated within the context of relations between Russia and Ukraine, it is broadly relevant to other elements of Great Power Competition.

The remainder of this post examines three aspects of Great Power Competition that are relevant to the Russia-Ukraine situation and that also raise important questions related to the law of armed conflict. While Russia’s behavior implicates both the in bello and ad bellum strands of the law of war, except where explicitly noted otherwise, we limit our discussion to in bello issues (which we refer to as the law of armed conflict).

“Large-Scale Military Operations” and the Law of Armed Conflict

For some time, references to “grey zones” and operations below the armed conflict threshold have been common in law-of-war discussion and analysis. Moreover, States conduct military operations in domains such as cyber and space where attribution is difficult or impossible and physically destructive effects are rare (at least thus far). In these situations, the difficult political, strategic, and legal calculations we raised in our prior post will persist. No doubt, Russia and others will conduct operations that place pressure on the armed conflict legal threshold to exploit the challenges associated with these calculations.

However, the Russian troop buildup near Ukraine offers an opportunity to examine a separate element of potential great power armed conflict—large-scale military operations. These operations consist of “extensive joint combat operations in terms of scope and size of forces committed, conducted as a campaign aimed at achieving operational and strategic objectives.” The U.S. Army describes such operations on land as involving “sustained combat operations involving multiple corps and divisions” (with corps typically containing two to five divisions of approximately 15,000 soldiers each). The Russian troop buildup on the Ukrainian border easily fits the size and scope envisioned by large-scale combat operations.

Obviously, such conflict would be vast in scale and highly destructive. The law of armed conflict is replete with standards that require judgment to balance competing factors. These include notions of “reasonableness,” “feasibility,” “definite military advantage,” and “civilian harm.” Furthermore, these standards are prospective, requiring commanders and other combatants to evaluate their relative weight based on highly ambiguous factual circumstances. The deadliness and destructiveness of large-scale combat operations will impact the way combatants apply these standards.

Consider, for example, Russia’s reported deployment of hundreds of tank and field artillery weapons near the Ukrainian border. Such vehicles and weaponry are notoriously difficult to destroy. As a result, belligerents must deploy anti-tank weapons and methods of warfare that are highly destructive. The resulting combination of immense military capability and high-stakes battle could compel belligerents to forego self-restraint. Parties will likely marshal significant combat power toward the goal of quick and complete destruction of the opposing forces.

Importantly, the law of armed conflict anticipates substantial resorts to lethal force. For example, the principle of military necessity recognizes belligerents’ authority to apply sufficient combat power to achieve the “complete or partial submission of the enemy at the earliest possible moment with the minimum expenditure of life and resources.” Nor does the law of armed conflict necessarily prohibit extensive collateral damage during such operations. The principle of proportionality only forbids those attacks in which the expected incidental loss of civilian life, injury to civilians, damage to civilian objects, or a combination thereof, would be excessive compared with the concrete and direct military advantage anticipated. Considering the high stakes of such combat operations, belligerent parties may reasonably conclude that substantial military advantage would ensue from such attacks. As always, interpretation and application of the law of armed conflict must account for the nature of war and the character of twenty-first century armed conflict (see Professor Eric Talbot Jensen’s comments here).

In this regard, it is worth reiterating, as we argued in our earlier post, that leaders of great powers and the general public must differentiate policy constraints that characterized the counterinsurgency and counterterrorism operations of the last twenty years and legal restraints that govern armed conflict. An armed conflict between Russian and Ukrainian forces—and other States that could join either side—would likely afford less space for the policy constraints of “near certainty” in targeting operations aimed at ensuring civilians would not be injured or killed.

Means and Methods of Warfare

Large-scale military operations necessarily implicate issues related to the means and methods of warfare associated with conventional warfare. As already noted, this includes armored forces capable of massive destruction that feature advanced protective capabilities. But States should also expect significant developments in emerging technology that place further pressure on the law of armed conflict. For example, in early 2021, reports surfaced of a Turkish-made drone equipped with machine learning algorithms that enable it to operate autonomously in some respects. The interim Libyan government reportedly used the drone, known as the Kargu-2, to attack rival, Russia-supported forces. (See Professor Chris Jenks’s comments here discussing this and another potential deployment of autonomous systems in the 2020 armed conflict between Armenia and Azerbaijan.) This is perhaps the impetus behind Russia’s development of drones capable of engaging other drones directly in combat. Recently, Russia tested this drone technology over Crimea, which most certainly was intended to signal its deployment in a potential Russian invasion of Ukraine.

These technical developments implicate questions related to preserving human control and judgment in the targeting process. To identify just one example of such questions, States must grapple with whether the delegation of some targeting decisions by humans to non-human capabilities such as autonomous weapons systems will be an option under the law of armed conflict. From our vantage point, current estimates about the character of future warfare will render the significant involvement of non-human capabilities in targeting decisions essential to any hope of operational success, at least in some contexts.

The U.S. Army, in developing concepts for future warfighting, anticipates an operational environment in which the speed and tempo of warfare reaches levels so far beyond human cognitive capabilities that belligerents must delegate at least some aspects of military decision-making to non-human, algorithmic-based tools and capabilities. This is not to suggest an approach in which humans turn warfighting over to machines. Rather, it suggests a more nuanced situation in which humans monitor a series of complex, interrelated delegations (to both subordinate humans and non-human capabilities) of authority, adjusting such delegations based on operational circumstances.

Multi-Domain Operations

Armed conflict in the context of Great Power Competition undoubtedly will feature military operations conducted through all domains of warfare, including cyber and outer space. Indeed, the United States military is in the midst of a major doctrinal shift to an operational concept marked by multi-domain operations (MDO). The MDO concept brings to bear kinetic and non-kinetic combat force to defeat peer and near-peer adversaries in a contested, access-denied operational environment. MDO emphasizes activities across the divide between peacetime and wartime, the ability to penetrate and disrupt peer adversaries’ robust anti-access and area denial systems, and exploit the resultant freedom of maneuver.

The shift to MDO is not merely conceptual. It has also played out in practice. As with autonomous systems, recent examples of MDO have provided a glimpse into the future of warfare. For example, during the 2008 armed conflict between Russia and Georgia, Russia—in support of its conventional operations—engaged in cyber operations aimed at Georgian government websites, media entities, and business organizations. A more recent example, although not as part of an armed conflict, involved cyber operations between Israel and Iran. While covert operations between the two States have mostly been aimed at military and government targets, recently the two States have engaged in operations against civilian entities such as a fuel distribution system. Finally, in what is likely preparation for the expansion of armed conflict to outer space, Russia recently launched a missile at an inoperable, 4,400-pound satellite, dispersing thousands of pieces of space debris.

These operational developments indicate that the troop buildup on the border of Ukraine includes a multi-domain aspect in which Russia’s cyber capabilities support a potential invasion. This will raise critical questions about targetability of space objects and cyber “objects,” and how the law of armed conflict applies in non-kinetic military operations. (For a valuable overview of the international legal framework that applies to Russian cyber operations against Ukraine, see Professor Michael Schmitt’s recent Articles of War post.)

First, the applicability of many law-of-armed-conflict rules to cyber and space operations will depend—as a threshold matter—on whether such operations constitute “attacks.” This question is important because many, if not all, targeting rules under the law of armed conflict are limited to operations that qualify as attacks, defined as “acts of violence against the adversary, whether in offense or in defense.” This contested but as yet unresolved question serves as a threshold for the potential legal regulation of many cyber operations. Prominent scholars have sought to address this and other questions. States must do the same.

Second, even assuming the applicability of targeting rules under the law of armed conflict to non-kinetic cyber and space operations, serious questions remain how legal terms developed in the age of conventional warfare apply to these new domains. For example, under the principle of distinction and its derivative rules, civilian objects may not be objects of attack. Civilian objects are those objects that do not qualify as military objectives. The latter consist of “those objects which by their nature, location, purpose or use make an effective contribution to military action and whose total or partial destruction, capture or neutralization, in the circumstances ruling at the time, offers a definite military advantage.”

This legal framework poses significant challenges for operations conducted in the cyber domain, characterized not by a clean demarcation between civilian and military infrastructure, but rather by a geographically vast, interconnected and interdependent network of communication technology often serving both civilian and military purposes. Given the civilian object–military objective framework, it is uncertain how effective the rules related to distinction can be. Rather, protection for cyber and space infrastructure that serves civilian purposes will be furthered primarily through the principle of proportionality, which prohibits attacks which cause excessive collateral damage and requires belligerents to implement feasible precautions to protect civilians and civilian objects.

However, application of these rules in the context of a multi-domain invasion between Great Powers—such as the potential Russian invasion of Ukraine—is no easy task. As discussed above, the likely intense scale of hostilities combined with the perceived stakes of winning or losing will significantly color the belligerents’ assessment of terms such as “concrete and direct military advantage.” Further, belligerents will be strongly tempted to engage in non-kinetic cyber and space operations against civilian infrastructure, both to preoccupy the adversary with domestic concerns as well as to undermine civilian resolve and support for the State’s war efforts. Once again, leading scholars have begun the work of assessing how the law of armed conflict applies in emerging domains of war. Most prominently, the Tallinn Manual 2.0 comprehensively analyzes how international law, including the law of armed conflict (see chapter 17) applies in the cyber domain.


This post’s purpose was twofold. First, Russia’s recent military buildup at the border of Ukraine afforded us an opportunity to revisit the concept of Great Power Competition and examine its law-of-armed-conflict implications. Indeed, this troubling development provides greater detail and perhaps clarity about what such competition—should it devolve to armed conflict—would look like in practice. It is likely that the combination of belligerents engaged in large-scale military operations and the deployment of emerging forms of battlefield weaponry and technology poses significant interpretive challenges for the law of armed conflict.

Second, and closely related to the first, we wished to highlight the need for Great Powers to be mindful of their legal obligations in the conduct of hostilities under the law of armed conflict. States must give due consideration to these obligations not only during but also before armed conflict. These legal obligations include those highlighted above but also include restrictions on the use of force found in the jus ad bellum as well as the threshold questions lying at the heart of the jus in bello, such as the classification of armed conflict and the classification of persons and groups on the battlefield.

Great Power Competition and the risk of armed conflict between States of enormous power and resources is not a hypothetical concern, nor is it one which resides in the distant future. Rather, the possibility of such conflict has arrived. The Russian military buildup at the border of Ukraine serves as a prominent example of its arrival. States and scholars concerned with the law of war must wake up to this reality.


BG Shane Reeves is the 15th Dean of the Academic Board of the United States Military Academy, West Point.

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.