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Thousands of nontraditional fighters have joined the Ukraine war

That puts civilians at risk, research shows

Volunteer soldiers from the Dnipro area relax at their outpost in Ukraine's Kramatorsk region on July 1. The men in the unit come from various backgrounds, one a police officer, one a farmer, one a retired television cameraman and one a college professor. (Scott Olson/Getty Images)
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As Russia’s invasion of Ukraine enters a fifth month, media reports continue to detail the heavy toll on Ukraine’s civilian population. Less media attention, however, has been paid to the humanitarian impact arising from the influx of foreign fighters, mercenaries, civilian volunteers and other nontraditional armed combatants — fighters not formally integrated as members of the professional armed forces of Russia or Ukraine. This month, for instance, reports emerged that Russian forces are now recruiting prisoners to fill depleted front-line units.

But nontraditional combatants typically have less training and less capacity to abide by the norms of international humanitarian law — the legal rules known also as the “law of war.” Indeed, nontraditional combatants in Ukraine have been associated with some of the worst atrocities of the war.

What do we know about the role and operations of nontraditional combatants? Our work suggests three key points on how these fighters can impact the protection of civilians in Ukraine.

Why do Russia and Ukraine exchange their prisoners?

Nontraditional combatants come in many forms

Recent headlines have highlighted the dizzying variety of nontraditional combatants and groups in the conflict. Estimates vary — several thousand of these fighters, coming from both inside and outside of Ukrainian and Russian territory, may have taken up arms on both sides.

The initial invasion inspired thousands of Ukrainian civilian volunteers — ordinary civilians mostly without military experience — to join Ukraine’s military-organized “Territorial Defense Forces” and defend the Ukrainian homeland from invasion.

Foreign volunteers have also augmented fighting forces, many with combat experience from Iraq, Afghanistan and Syria as part of Ukraine’s International Legion of Territorial Defense. And there are signs that Ukrainian civilians, working in the capacity of resistance fighters, have stepped up attacks on Russian targets in eastern Ukraine.

Across the front lines, Russian forces have been similarly supplemented by volunteers, as well as by armed groups not wholly under the control of government forces. Paid mercenaries, along with foreign fighters and other forces from Chechnya, Syria and elsewhere, have also joined the Russian war effort. Notably, the Russian military has relied extensively on the Wagner Group, a Russia-based mercenary organization implicated in a number of alleged war crimes throughout the Middle East and Africa. These examples reveal the breadth and diversity of nontraditional fighters operating on Ukraine’s battlefields.

Looser command structures can mean more war crimes

Research shows that aspects of these nontraditional armed groups create additional risks for civilians. The weaker command structures implemented by nontraditional armed groups can decrease their capacity to comply with international laws of war, for instance. Commanders can’t always directly monitor the activities and conduct of fighters on the front lines. Military commanders in war thus face a stark command dilemma — they need to motivate their fighters to employ violence, but they also need to control and constrain this violence.

Additionally, the chaotic nature of warfare can increase the likelihood of civilian harm, especially where the lines between civilians and combatants become blurred — or when fighters believe targeting civilians will help them to achieve battlefield gains.

Why Russia may be taking Ukrainian children

Extensive research shows that to regulate the use of force, military organizations often institute enforcement structures, including codes of conduct, regulations for military justice and rules of engagement, that limit what actions are authorized in combat.

Nontraditional combatants, however, often fight under far less strict command and enforcement structures. These weaker command structures can inhibit commanders’ ability to constrain fighters’ conduct, leading to increased war crimes and other violations.

Less training in the laws of war can also lead to more violations

In addition to enforcing the rules of conduct, military commanders also rely on training in organizational values to influence the behavior of fighters under their command. Recent research shows how factors such as norms, ideology, political education and military culture can socialize combatants to the military’s organizational values, shaping soldiers’ views about appropriate behavior in combat. Recent survey research by one of us finds that intensive training can increase the adoption of civilian protection norms, known also as “norms of restraint.”

Professionalized military forces like the U.S. and British armies — and increasingly the Ukrainian army — devote significant training to instilling within the ranks the principles of international humanitarian law and ethics. While this training often requires a greater investment in time and resources, shaping combatants’ views of appropriate battlefield conduct can be a more effective method of constraining violence than simple rule enforcement. This training is particularly important for battlefield environments, where combatants often operate outside commanders’ direct control.

Conversely, nontraditional combatants, including those operating in Ukraine, often have lower levels of training and generally much less exposure to the rules of international humanitarian law. Individual fighters, in particular, may join the conflict with little military experience or with previous military experience that paid less attention to protecting civilian lives. This lack of training and socialization in the law of war can thus lead to more atrocities in conflict.

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What does this mean for Ukrainian civilians?

These issues reveal that the presence of nontraditional combatants can make already dangerous modern battlefields more perilous for civilians. Armed groups, mercenaries, foreign fighters and other combatants who lack strong enforcement structures or intensive training in norms of civilian protection can create far greater risks for civilians. If countries wish to reduce these risks, our research suggests the importance of strengthening command enforcement structures and civilian protection training across the broad spectrum of armed groups engaged in conflict — both in Ukraine and around the world.

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Andrew M. Bell (@AndrewBellUS) is assistant professor of international studies at the Hamilton Lugar School of Global and International Studies at Indiana University-Bloomington and a visiting fellow at the U.S. Army War College.

Katherine Kramer is senior manager for protection of civilians at InterAction, a coalition of humanitarian and development NGOs working globally.

The views expressed in this work are the authors’ alone and do not necessarily represent the view of the U.S. Army or the U.S. government.