A migrant woman pulls a girl out of the water on the Greek island of Lesbos
A migrant woman pulls a girl out of the water as refugees and migrants arrive on an overcrowded dinghy in rough sea on the Greek island of Lesbos, October, 2015.
Dimitris Michalakis / Reuters

After the recent terrorist attacks in Paris, hostility toward refugees in many Western countries has surged. Last week, France’s anti-immigration National Front, already popular before the attacks in Paris, achieved its best ever results in the first round of regional elections, winning almost a third of the vote. In the United States, meanwhile, 31 governors and almost all the Republican presidential candidates oppose further refugee settlement in the United States.

Fear of refugees following a terrorist attack is a natural reaction, and some confusion over the connection between refugees and violence is understandable. Even the academic community, which has studied the topic for years, has yet to settle on an understanding of the relationship between the two.

But making efforts to block people fleeing to the West from war zones is the wrong response to the horrors of Paris. The latest evidence suggests that the connection between refugees and terrorism is tenuous. The West can take in refugees without jeopardizing its national security.


The two main grounds for caution in welcoming people from conflict-torn regions are intuitive and widely shared. The first is that individuals seeking refuge across international borders threaten to destabilize the countries that take them in. 

Some research supports this view. Experts have theorized that refugee communities may include political activists and insurgents who mobilize and recruit in the receiving country, giving rise to the purported phenomenon of the “refugee-warrior.” Refugee camps serve as potential military bases from which refugee-warriors can wage insurgencies. Others, including the political scientists Idean Salehyan and Kristian Skrede Gleditsch, have argued that refugees, as they themselves flee violence, are a mechanism by which internal conflict in one state can spill across borders. People leaving war zones may bring weapons, terrorism, and militant ideologies with them.

People gather to protest against the United States' acceptance of Syrian refugees in Olympia, Washington.
People gather to protest against the United States' acceptance of Syrian refugees in Olympia, Washington, November 2015.
David Ryder / Reuters

The second argument against welcoming refugees is that although the vast majority of refugees may be peaceful, they may unwittingly shelter a violent minority. Markus Söder, a conservative politician in Bavaria, which initially received refugees released from Hungary, expressed this perspective succinctly: “Not every refugee is an Islamic State terrorist. But to believe that there is not a single fighter among the refugees is naive.”   

Both these arguments, intuitive as they may appear, are flawed. Most important, the U.S. screening process designed to protect against terrorist infiltration is extensive. Terrorists who wish to enter the United States can find far more accessible routes than by posing as refugees. In Europe, porous borders and the inability to agree to a common refugee policy mean that the refugee route is a more feasible option for terrorists, but it remains cumbersome for a sophisticated operation.

The West can take in refugees without jeopardizing its national security.

But screening is not the only reason most refugees are unlikely to engage in violent crime or terrorism. Of the 18 million refugees in the world today, the United Nations High Commissioner for Refugees estimates that more than half are children. Among the adults, the vast majority are civilians who have never engaged in combat. Instead, they are mostly incapable of—or averse to—fighting. Consider, for instance, estimates that “one in five [Syrian] refugees is affected by physical, sensory, or intellectual impairment [while] one in seven is affected by chronic disease.”

A 2008 survey of Darfurian refugees in Chad provides further evidence of refugees’ psychological aversion to conflict. Those who had personally experienced violence during the civil war expressed less interest in retribution and a greater desire for peace than those who had not.

As for the academic evidence on refugee-warriors, scholars have found previously that the appearance of refugees and the outbreak of conflict tend to occur in the same place and time. But this correlation is unsurprising: substate conflict generates more refugees than any other source, forcing citizens to flee their homes and often preventing them from returning.

A much more difficult question to answer is whether the spread of refugees also tends to produce violence itself.

To investigate whether refugees spread violence and instability in their host communities, two of us (Shaver and Zhou) analyzed highly detailed data provided by the United Nations on the precise locations of refugee settlements throughout the world over the last two decades. The data enable more fine-grained analysis than previous studies, whose authors had to rely on broad, country-level measures. 

This data can determine much more precisely whether the presence of refugee populations is linked to the outbreak of localized violence or instability. The results are clear: there is no positive association between refugee populations and subsequent outbreaks of civil violence.

Instead, the opposite may be true. Areas hosting refugees appear to be more stable in the years following their arrival. This may be the result of domestic and international efforts to ensure stability in such areas, including the deployment of security personnel and screening staff to affected areas. States’ preemptive measures to prevent instability can be effective.

A family of Syrian refugees wait for a registration procedure in Agathonisi, Greece.
A family of Syrian refugees wait for a registration procedure in Agathonisi, Greece, September 2015.
Alkis Konstantinidis / Reuters


The case for fearing refugees is similar to the way many used to think about poverty and terrorism. Following the 9/11 terrorist attacks and during the Iraqi insurgency, policymakers at the highest levels of government gave voice to the narrative that poverty generates terrorism and other violent acts of desperation. Years of expert study discredited this view. Economists, including Princeton Professor Alan Krueger, showed that terrorists are no more likely to come from the poorest ranks of society than they are from the richest.  

But if poverty does not tend to produce terrorism, social inequalities very well might.

Researchers have found evidence that inequalities increase grievances across ethnic cleavages and, ultimately, the likelihood of civil violence. Analyzing the outbreak of violence in India, one expert has found that “economic and political discrimination explain conflict outbreaks.” Related work on recent civil conflict in Nepal shows that areas of relative deprivation make fertile ground for the Maoist insurgency.

These findings are relevant today. For years, groups such as Amnesty International have argued that many of Europe’s Muslim populations face discrimination in jobs and education. Recent academic research provides a more rigorous basis for these claims. A study in the prestigious Proceedings of the National Academy of Sciences, for instance, found that in France, anti-Muslim discrimination is responsible for significant disparities in joblessness. A Christian candidate is more than twice as likely to be invited for an interview as an equally qualified Muslim.

But if poverty does not tend to produce terrorism, social inequalities very well might.

As the Princeton University terrorism expert Jacob Shapiro has shown, terrorism is simply a tactic available to violent political organizations. In less developed countries, social inequalities may result in insurgency or civil war. In developed Western countries with strong national security programs in place, such inequalities may result in terrorism, a weapon of last resort for those who cannot challenge the state more directly.


There are no grounds to suspect that those fleeing Syria and Iraq pose a bigger threat to the communities that receive them than did previous refugees. Whether they remain unthreatening will depend on how well they assimilate into the areas in which they settle. In the end, the reception they receive from local populations and host states will matter far more than where they come from.

For Western politicians, this means discarding the convenient fiction that refugees are temporary visitors who will shortly return home. Only then can sensible policies, such as language training, work authorization, and programs to enroll children in local schools, be sold to a skeptical public.

It would be foolish to claim that resettled refugees will never commit an act of violence against their host communities, politically motivated or not. Any large group of people—whether refugees or locals—will include a wide range of personalities, some more willing than others to behave violently. But restricting Syrian and Iraqi refugees from building a new life in safety is likely only to exacerbate the terrorist risk receiving nations face. If these communities perceive discrimination from their hosts, radical Islamic ideology may find a receptive audience, particularly among second- and third-generation children of refugees.  

High-minded humanitarianism should not override security interests. But even from the perspective of a narrow conception of national security, refugees are typically nonthreatening populations in the years following their arrival. If there is little reason to fear refugees, the question should be how much the West can and should help them and how best it can welcome them as productive members of their societies.

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  • ALEX BOLLFRASS is a doctoral candidate at Princeton University’s Woodrow Wilson School of International Affairs and a Fellow at the Stimson Center. ANDREW SHAVER is a doctoral candidate at Princeton University’s Woodrow Wilson School of Public and International Affairs. He served previously as a Pentagon analyst and Foreign Affairs Fellow with the U.S. Senate. YANG-YANG ZHOU is a doctoral candidate at Princeton University’s Department of Politics and a National Science Foundation Fellow. She has previously worked with refugees and asylum seekers at the Bellevue/NYU Program for Survivors of Torture.
  • The views expressed in this article are those of the authors and do not reflect the official policy or position of the Department of Defense or the U.S. government.
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