U.N. peacekeepers from Rwanda serve at a U.N. base in Malakal, South Sudan, in 2016. (Jane Hahn for The Washington Post)

Over the past 20 years, U.N. peacekeeping deployments have increased by more than 600 percent. Currently, the United Nations manages 14 peacekeeping operations worldwide, staffed by more than 95,000 military personnel, police, civilians and volunteers.

For almost all of these, a common mandate is to protect civilians — which is important not just in immediately saving lives, but also in sustaining peace over the long run. Recent academic research has focused on how well peacekeepers do at reducing conflicts’ virulence and spread.

But do armed peacekeepers actually protect civilians from harm? That’s been debated lately. A recent report, delivered to U.N. Secretary General António Guterres by retired Brazilian Lt. Gen. Carlos Alberto dos Santos Cruz, recommends boosting peacekeepers’ war-fighting abilities. But others, including Professor Lise Howard, argue that militarization isn’t what keeps the peace.

We set out to determine whether peacekeepers’ military force helps to protect civilians. Here’s what we found.

How we did our research

Assessing military peacekeepers’ efficacy in keeping the peace is a challenge, because troop deployments are only one component of an array of efforts. U.N. peacekeeping missions include representatives from the Office of Rule of Law, the Electoral Assistance Division and the Office of Coordination of Humanitarian Affairs, all of whom bring critical help in rebuilding war-torn societies and setting up a functioning post-conflict democracy.

Complicating efforts to assess peacekeeping forces even more, the overall number of peacekeeping forces often signals to the international community how important the situation is — and encourages (or discourages) others’ diplomatic efforts.

We studied four peacekeeping missions: the United Nations African Union Missions in Darfur (UNAMID) from 2008-2016, where approximately 13,617 troops were deployed by 2016; the United Nations Organization Stabilization Mission in  Congo (MONUSCO) from 2011-2016, with approximately 16,957 deployed troops in 2016; the United Nations Operation in Côte d’Ivoire (UNOCI) from 2006-2016, where approximately 1,889 troops were deployed in 2016; and the United Nation Mission in South Sudan (UNMISS) from 2011-2016, with 11,189 deployed troops in 2016.

We specifically examine the number of civilians killed at the local level each year, using data from the Armed Conflict Location and Event Data project (ACLED). We didn’t just count the number of U.N. peacekeepers, a number that includes administrative and support staff; we specifically determined and counted how many combat-ready companies of troops were on the ground in each local area. That matters, because it tells us how many U.N. forces are available to protect civilians, without counting personnel who have little role in accomplishing the mission’s primary objective.

Military peacekeeping forces do protect civilians from harm

Even though U.N. peacekeeping forces tend to deploy to countries where violence is most entrenched, we find that peacekeepers still help protect civilians from harm.

For example, according to our data, the peacekeeping bases in  Congo dramatically lowered civilian violence in nearby regions, despite the fact that overall civilian fatalities in the country increased from 2011 to 2016, from 193 to 792. However, fewer civilians died in areas protected by U.N. peacekeeping troops. The presence of combat-ready peacekeepers helped protect civilian lives.

How do peacekeepers reduce violence against civilians?

After a war, survivors are often still hostile toward one another, competing both for local political control and for such scarce resources as food, water and mineral wealth. At times, political groups urge their supporters to fight — especially as elections near, when political rivals target their opponents’ supporters to stop them from voting and to show their own determination to control local areas.

But some of that hostility can dissipate when peacekeepers are on the ground as well. Research shows that their presence can de-escalate tension by facilitating communication and preventing misunderstandings among former combatants; by serving as a physical buffer between former adversaries; and, through monitoring and oversight, by discouraging those who would sabotage the peace. As a result, peacekeeping units not only can save lives, but also can make it possible to build effective governing institutions — which is the only way to eliminate the economic and political conditions that produce violence.

So peacekeepers do protect civilian lives after conflict. Both government and rebel groups are less likely to harm civilians in areas where peacekeepers have deployed. This is a welcome finding.

But there’s a catch

Our study also examines both government and rebel violence against civilians after conflict in the places where peacekeeping forces are deployed. And with this information, we find that peacekeepers are less likely to respond to government attacks against civilians than rebel group attacks.

While peacekeepers deploy to areas experiencing rebel violence, we do not see the same reaction when government forces attack civilians. That may be because peacekeepers’ mandates note that the host government is principally responsible for protecting civilian lives and mission commanders understand that deployments must ultimately be approved by host governments. At the end of the day, confronting host government forces risks mission consent and success.

That suggests a larger problem. If peacekeeping nurtures illiberal regimes, can it actually foster long-term peace and reconciliation?

Brandon Prins is professor of political science and a global security fellow with the Howard Baker Center for Public Policy at the University of Tennessee-Knoxville.

Anup Phayal is assistant professor of political science at the University of North Carolina, Wilmington.