A displaced Syrian child, fleeing from Deir Ezzor, a city besieged by Islamic State fighters, carries broomsticks as he walks through a refugee camp Feb. 1 in al-Hawl, located near the Iraqi border in Syria’s northeastern Hasakah province. (Delil Souleiman/AFP via Getty Images)

The Trump administration’s executive orders on immigration have targeted refugees as a particular threat to national security, despite a lack of evidence that this is the case. To the contrary, American and European unwillingness to resettle refugees away from the Middle East could present a much greater threat to national and global security over the long term.

The reluctance to accept asylum seekers and resettle refugees has kept many of those fleeing conflict in Syria in neighboring countries, where they face deteriorating conditions and few prospects. The growing refugee populations place extreme pressure on poor and middle-income countries, increasing the risk of state collapse.  Refugees themselves are often targets for militant mobilization and radicalization — thus expanding the conflict in the Middle East.

Are refugees a danger to the United States?

President Trump has linked refugees, particularly those from Muslim-majority countries, with terrorism. Excluding these, he argues, will make the United States safer. His March 6 executive order on immigration, currently under a temporary stay, included shutting down the U.S. Refugee Resettlement Program for 120 days.

Further, the White House ordered that the number of resettled refugees, which the Obama administration set at 110,000 for fiscal year 2017, be capped at 50,000. This is in litigation before a federal court in Maryland. However, the Refugee Act of 1980, which created the resettlement program, gives the president broad authority to set the number of refugees the United States will accept in a given year, so the program may well be scaled back in the future.

There is little evidence that refugees present a danger, however. Resettled refugees undergo extensive background checks that often take two years or more, and are the most thoroughly vetted of any immigrant group. As a practical matter, the refugee resettlement process would probably be a prohibitively cumbersome mechanism for the infiltration of militants into Western countries. The perpetrators of recent terrorist attacks in Paris, Orlando and San Bernardino, Calif., were citizens or permanent residents.

There’s a broader threat to global security

There is evidence, however, that national-security interests may be threatened if refugee resettlement is halted. The world is in the midst of the largest forced migration since World War II. Without either ending the underlying causes of the migration or increasing the asylum capacity within the international community, most of those seeking refuge from the conflict will remain in countries in the Middle East and Africa.

According to the UNHCR, over 3 million refugees, mostly from the Syrian conflict, are now in Turkey. That’s nearly 5 percent of the population. About 10 percent of them live in massive, ungoverned refugee camps — potential sources for extremist mobilization and transnational criminal activity, as Sarah Lischer has documented. In southeastern Turkey, where 38 percent of the refugee population is concentrated, opportunities for employment are scarce, and violence has increased significantly.

In Jordan, the government has sought to contain refugee inflows from Syria by concentrating tens of thousands of refugees in camps along the border, such as Ruqban and Hadalat. Armed militias have formed in these camps, which have been the target of Russian airstrikes.

Lebanon has the world’s highest number of refugees per capita, with an estimated 1.2 million refugees, mostly from Syria, in a country with a population of roughly 4.4 million. While Lebanon officially has a “no camps” policy, 90 percent of these refugees are located in just 251 localities, which are some of Lebanon’s poorest.

There’s a dangerous precedent here — Afghan refugees in the 1980s and 1990s

The concentration of refugees in the poorest regions of countries in the Middle East echoes the plight of refugees from the conflict in Afghanistan in the 1980s and 1990s, when over three million Afghan refugees fled to Pakistan after the 1979 Soviet invasion. Most of these refugees ended up in camps in the Federally Administrated Tribal Areas and present-day province of Khyber Pakhtunkhwa, the most underdeveloped regions in the country. These camps became the primary recruiting ground for some of the most radical and brutal mujahidin militias, particularly Gulbuddin Hekmatyar’s Hizb-i-Islami. The Taliban movement began among Afghan refugees studying in seminaries in northwest Pakistan.

These refugee camps have remained a key recruitment ground for the Taliban and continue to destabilize Pakistan. Many of Pakistan’s problems with internal order, from extremist violence and sectarian conflict to drug trafficking and the proliferation of small arms, have their roots in the lawlessness of these camps. New militant groups have been more recently mobilized within the refugee population. Such disorder helped break down governance arrangements within the country’s tribal agencies. This led to the consolidation of the Tehreek-e-Taliban Pakistan, the group responsible for a nearly decade-long insurgency aimed at destabilizing the Pakistani state.

There are crucial differences between Afghan and Syrian cases, but parallels remain

Unlike Afghan refugees in Pakistan, most Syrian refugees are not restricted to camps. And there is less evidence at present of recruiting and arming militias from among refugees in the region, as happened with recruitment of the Afghan mujahideen.

But the parallels may well grow stronger as the conflict continues. The lack of employment opportunities and the concentration of refugee populations in the poorest regions of host countries create de facto refugee camp conditions. Syrian refugees in Lebanon are regularly denied work permits, which forces them into the informal economy. These restrictions create potential conditions for expanding the Syrian conflict well beyond its borders.

Populations languishing over years in poor conditions, without access to jobs or education and separated from family and kin, can be ideal targets for radicalization. At present, the U.S. and Europe rely on the stability of countries like Turkey and Lebanon — but the long-term presence of millions of refugees puts great strains on services and governance in these middle-income countries.

There is a danger that the prolonged stay of 4 million Syrian refugees might weaken the stability of Turkey, Lebanon, Jordan, Iraqi Kurdistan, Algeria and Tunisia — all countries that have thus far escaped the pressures of state collapse following the Arab Spring.

If permanent political settlements aren’t an option, the only solution to the crisis is to move large number of refugees to countries better equipped to absorb them, thus giving them access to opportunities until the conflict is over. As a matter of simple geography, most asylum applicants make their way to Europe, having plausible, if still very dangerous, land and sea routes into the continent.

In 2016, Norway, Switzerland and E.U. member states saw 1.2 million asylum claims, the vast majority from the Middle East. However, U.S. policy has historically responded to spikes in asylum claims elsewhere by increasing refugee resettlement in the United States. Relocation is critical for alleviating the crisis in the camps, and thus forestalling a much broader conflict spanning the entire Middle East.

Jonah Eaton is staff attorney at the Nationalities Service Center in Philadelphia and guest lecturer in refugee law at the University of Pennsylvania Law School.

Adnan Naseemullah is lecturer in international relations and South Asia at King’s College London.