MORE THAN two hundred thousand people have died in the Syrian civil war, and the conflict has produced mass refugee flows and internal displacement. The Islamic State controls large swaths of territory and has taken the war into Iraq, leading to thousands of deaths there. The Obama administration has responded by bombing the Islamic State and, less successfully, trying to build up various rivals to it, particularly in Iraq, but has refrained from a more massive and risky intervention that could either end the civil war altogether or embroil the United States further in a bloody and unwinnable conflict.
Given the dismal record of U.S. interventions in the Middle East, the administration’s caution is warranted. But its cautious approach also rests on the convenient assumption that the conflict will remain contained within Syria’s borders. In fact, civil wars like the one in Syria often shake the foundations of regional orders. They create massive refugee flows, spawn terrorist groups and radicalize neighboring populations. Neighboring states fear these consequences and provide arms to fighters or even intervene with their own military forces in order to secure their interests. Such interventions often worsen the bloodletting and, by changing a local conflict into a regional one, spread the conflict even further.
For both strategic and humanitarian reasons, Washington should focus on more than just the Islamic State. It should also work to contain the violence in Iraq and Syria and the resulting spillover. This involves helping neighboring states police their borders, manage refugees and fight terrorism. It also means discouraging shortsighted interventions. These efforts to reduce the risk of spillover are by no means foolproof (and some will achieve at best limited results), yet they are necessary complements to other U.S. and allied strategies toward Syria and Iraq. If Washington plans to up its intervention in Syria and Iraq by intervening militarily or more aggressively backing the Syrian opposition, it will still take years to achieve lasting success. Containment is necessary in the interim. If, instead, the price of greater intervention is deemed too high, containing spillover is perhaps even more necessary to limit the damage. Moreover, containment is relatively cheap compared with the alternatives, and some of the measures do not require heroic efforts to achieve.
CIVIL WARS often spill over into neighboring states. This problem is particularly acute for more massive civil wars that have large death tolls and produce vast refugee flows. Since the end of the Cold War, conflicts in locales as diverse as Afghanistan, the Balkans, the Congo and Somalia erupted in neighboring states, leading to problems ranging from terrorism to new civil wars.
The conflicts in Syria and Iraq are especially prone to this phenomenon. Politics in the Arab world has long crossed borders, as a common Arab identity is strong while the national one is weak in many states. As political Islam has risen in influence, a shared sense of religious identity has become another source of unity that crosses borders. Sectarianism is an important part of the conflicts, and this has agitated both Sunnis and Shias around the Muslim world. Neighboring states have responded to popular anger along sectarian lines—and have exploited sectarianism to deflect domestic tension.
The conflicts also are at the center of the Arab world, a region of deep strategic interest to many states. Iran is propping up the Syrian regime with massive aid and its own forces. In addition, the Syrian regime has invited in nonstate Shia groups from Iraq and Lebanon to join the fray. Tehran is also working directly with Shia militias in Iraq, fighting the Islamic State but also spreading fear among Iraqi Sunnis that the Shia groups will, as many did in the past, serve as death squads and agents of Iranian influence. Russia, meanwhile, has long assisted Assad’s regime, and as of the fall of 2015 appears to be increasing its on-the-ground support.
The Syrian opposition receives support from Turkey and Arab states like Saudi Arabia and Qatar. These states all oppose Syrian president Bashar al-Assad, but they frequently back different opposition factions and contribute to the rebels’ lack of unity. Of more concern, in February 2015, the head of the National Counterterrorism Center testified that over twenty thousand foreign fighters from at least ninety countries had gone to Iraq and Syria to fight with Sunni groups like the Islamic State, with over 3,400 from the United States and Western Europe. The majority of the rest emanate from the Arab and broader Muslim world.
REFUGEES REPRESENT one form of spillover. Refugees are both a humanitarian and a security challenge. Violence or the fear of violence often drives refugees from their homes, leaving them politicized and vengeful. In their host countries, they are often poorly integrated and have few economic or political opportunities. Not surprisingly, many return to the fray, and the refugee camps themselves can become bases for militant groups of all stripes. Rival groups and threatened states may strike at the camps to stop this or take revenge, expanding the conflict. In Afghanistan, the Taliban emerged out of the Afghan refugee population in Pakistan, and refugees from Rwanda played an important role in sparking the Congolese war, the deadliest conflict since World War II. The Palestinian refugee flows of 1948 and 1967 spawned an array of dangerous terrorist groups, spread instability to neighboring states and led to proxy wars with the Palestinians themselves both victims and instigators.
The Syria conflict is the world’s largest current generator of refugees, and there is no comprehensive plan with appropriate resources for managing them. According to the United Nations High Commissioner for Refugees, by August 2015 the Syria conflict had produced four million refugees, with over 1.1 million going to Lebanon, over 1.9 million to Turkey, over 620,000 to Jordan and over 240,000 to Iraq (many of whom are now fleeing anew as the Islamic State spreads its area of control). The latest fighting in Iraq has led to three million more Iraqis being displaced as of June 2015. Many of the refugees are in camps, but in Turkey, Jordan and Lebanon many have also settled in urban areas. In Lebanon, Syrian refugee camps have at times served as bases for jihadist groups fighting in Syria. In the fall of 2015, the refugee crisis spread beyond the Middle East, with tens of thousands of refugees seeking refuge in Europe and roiling politics there.
Neighboring states, especially poor ones like Jordan and Lebanon, risk being overwhelmed. Many are not able to police the refugee camps or integrate the refugees living outside the camps in urban areas. Refugees are placing an intense burden on their host countries’ domestic services. Jordan, long hospitable to the influx of people, recently ended health care to Syrian refugees outside camps. Lebanon has attempted to solve the strain caused by the refugees by closing its borders to most Syrian asylum seekers. Host countries also have security concerns. In Jordan, most refugees enter through border crossings in areas under Islamic State control, causing infiltration concerns. The camps are likely to exist for years or even decades.
TERRORIST GROUPS thrive because of civil wars. Hezbollah grew out of the Lebanese civil war, and Al Qaeda nurtured itself during the Afghan civil wars in the late 1990s. Movements associated with or inspired by Al Qaeda in places as diverse as Pakistan, Iraq, Yemen, Algeria and Mali all also flourished in civil wars. Al Qaeda in Iraq used Syria as a base area to rebuild; when war broke out there, it joined the fray, eventually splitting into the Islamic State and Jabhat al-Nusra. These are two of the most important rebel groups in Syria today, and the Islamic State has returned in force to Iraq, controlling major cities like Mosul as well as many Sunni areas.
Neighbors are already suffering from terrorism. Over the past year, Sunni jihadists, many of whom are affiliated with Jabhat al-Nusra, have attacked Shia interests in Lebanon on multiple occasions. The conflict has also reinvigorated Lebanese Sunni jihadist groups. The Islamic State has attempted attacks in Jordan and claimed responsibility for the bombing of Shia mosques in Saudi Arabia and Kuwait. Its affiliate groups have carried out operations in Egypt, Libya and beyond.
Jihadist groups are particularly likely to attract foreign fighters, an important form of spillover. Highly ideological and not tied to local communities, these foreigners are often more ruthless and brutal than local fighters, and they in turn proselytize and try to radicalize groups further. Terrorism expert Peter Neumann told CBS News that Syria is the top “mobilizer for Islamists and jihadists in the last 10 or 20 years . . . more people from Europe are being mobilized than in all the other foreign conflicts that have happened for the past 20 years taken together.” If Assad falls or cannot reassert full control over his territory, some will stay on in Syria to try to transform it into what they see as a true Islamic state—one that has no room for Syria’s religious diversity or even for moderate Sunnis. The Islamic State and other jihadists are also likely to aid like-minded groups among Syria’s neighbors, giving them a base from which to train and operate within territory the group controls. Others will return home, and counterterrorism officials fear they will bring their dangerous ideas and skills with them. In the Arab world in particular, returning foreign fighters have been important in seeding new groups in their home countries, making existing groups more radical and otherwise fostering instability.
This problem is being felt far from the battlefield. Following the precedent set by Al Qaeda, which nurtured relations with like-minded groups and eventually made them formal affiliates, the Islamic State has used the conflict to grow in power and declare “provinces” in the Sinai, Libya, Saudi Arabia and Yemen, among other areas. The meaning of this affiliation is mostly unclear, and so far the Islamic State “provinces” have not dramatically altered the courses of local civil wars (or, in the case of Nigeria, Boko Haram’s assumption of the Islamic State mantle has not changed the group substantially). However, in Libya, the Islamic State has deployed money and foreign fighters to help its local allies advance, enabling them to carve out small parts of the country and put them under Islamic State control.
CIVIL WARS also lead to the radicalization of politics in neighboring states. Refugees bring politics with them: the Palestinian cause was at the center of intra-Arab maneuvering for decades, and its turbulence led to coups and civil strife in many Arab countries. Similarly, terrorism, another effect of spillover, can destabilize neighboring state politics, weaken governments and allow regimes to exploit the violence to discredit their enemies. Some governments may step up repression to stop potential unrest, exacerbating concerns about discrimination. Finally, violence often highlights grievances or problems in another country, raising awareness and demands for better treatment.
Civil wars also create new issues that upset delicate equilibria in local politics. In Iraq, Jordan and Lebanon, large refugee flows are altering fragile demographic balances, leading some communities to oppose the refugee presence for fear that refugees will aid their local enemies. The civil war in Afghanistan spilled over into Pakistan, with groups like the Pakistani Taliban terrorizing Pakistan itself and poisoning relations between Shia and Sunni there. The spread of radical ideas from one country to another is particularly likely in conflicts like that in Syria, where the people living across the borders enjoy family, linguistic, ethnic, religious and historic ties with Syrians. Alevis in Turkey have ties to Alawis in Syria; Syria’s Kurds have ties to Kurdish communities in Iraq and Turkey; and of course the Shia and Sunni populations of Iraq and Syria have sympathetic communities in neighboring states. These communities often demand their own governments intervene, and they often privately mobilize to provide their own assistance or gain government blessing and support to do so. In Lebanon and Iraq, the people are also split communally, and the government’s actions (or inactions) in Syria are yet another source of grievance. This radicalization was particularly visible in Iraq, where even before the Islamic State advanced there in 2014, the sectarian violence in Syria strained relations between the Sunni and Shia communities. In Saudi Arabia, too, sectarian rhetoric and anti-Shia violence are fueling tension between the kingdom’s Sunni majority and Shia minority.
ALL THESE pressures can contribute to regional intervention. Academic research indicates that the presence of civil wars increase the likelihood of conflict between states as neighboring regimes seek to shape the civil war’s outcome and manage its spillover effects. Pakistan sent its own military and intelligence officers to bolster the Taliban in the 1990s; Kenya intervened in Somalia to help push back Al Shabab; Rwanda, Uganda and other neighbors intervened in Congo to back favorites; and so on: the combination of perceived threat and opportunity has at times proved irresistible. The United States, too, sometimes intervenes when small civil wars became big ones.
In Syria, Iran intervened early in the civil war to prop up Assad, and its assistance may have been decisive in allowing the Syrian regime to survive the war’s initial years. Jordan and Turkey assist antiregime rebels, with Jordan shifting support from the Free Syrian Army to Syrian tribes, while the Iraqi government, somewhat more slyly, facilitates Iranian intervention on its territory. The Assad regime, weak and focused on holding on at home, has largely refrained from retaliating against neighbors supporting rebels, but it was reportedly behind a 2013 bombing in a Turkish border town that killed more than fifty people, mostly Turkish citizens. Turkey has joined the U.S.-led intervention against the Islamic State—but it directs the bulk of its military efforts against anti-Turkish Kurdish rebels who have based themselves in Iraq. The heightened sectarian environment and the growing Iranian-Saudi rivalry in Syria and Iraq have also led both countries to step up intervention in Yemen, which each sees as yet another front in the broader war. Substate groups like Hezbollah in Lebanon or Sunni tribes in Iraq also work with their favorites across the border. Intervention tends to produce a spiral, with intervention increasingly occurring because others are intervening.
SPILLOVER CANNOT be stopped completely, but it can be contained to minimize its effects. The goal of containment is to prevent the strife from spreading further and to stop outsiders from worsening the violence within Iraq and Syria, thereby making it at least somewhat more likely to peter out on its own. In practice, containment would involve several measures, each linked to a different dimension of spillover.
First, the refugees demand care—both because of the strategic risk they pose and because of the moral imperatives. Since the Syrian crisis broke out, the United States has provided billions of dollars of humanitarian aid, with much of that going to refugees or those within Syria. Outside of aid to those displaced inside Syria itself, Lebanon and Jordan are the largest recipients, and the United States is increasing aid to Jordan and providing loans for economic support. Europe has given comparable amounts to Syria’s neighbors and taken in many thousands of refugees.
This aid is significant, but a larger-scale effort is necessary to care for the refugees. Neighboring countries, especially the poorer ones like Jordan and Lebanon, need additional financial support to care for refugees in camps and to integrate them into society when possible. In Lebanon refugees have often settled into the country’s poorest neighborhoods, and their presence has exacerbated tension between Sunnis and Alawis in cities like Tripoli. Other states should help with the burden. When Hungary briefly stopped the transit of refugees in September 2015 and high-profile migrant deaths occurred elsewhere in Europe, it prompted broader soul-searching across the continent with Austria, Germany, and other countries vowing to take in significantly more refugees—an important step in the right direction. The United States plans to take in more Syrian refugees than before, but this number could still be increased further. More support for refugees allows the United States, for a fraction of the cost of significant military intervention, to offset some of the humanitarian horror of the war and reduce the risk of spillover from refugee flows.
HOST-COUNTRY efforts to police refugee camps also need international support. The large population of the camps necessitates large security forces to police them. In addition, intelligence assistance at times will be necessary to ensure that host governments are aware of potential militants and able to disrupt their activities.
In addition to caring for refugees, an effort should be made to resettle them far from the borders of the conflict zone and integrate them into their host societies, thus making them both less willing and less able to join or support militant groups back in their home countries. This will require host countries to accept that the refugees are likely to stay for the long term, a financially costly and politically contentious issue for them. The long-term cost of a failure to integrate is high. Marginalized refugees will not contribute to their host economies and may be a source of radicalism. In Jordan, half the population is officially refugees from the age-old Palestinian diaspora, the latest influx of Syrians, or the previous round of Iraq wars. In Lebanon, refugees make up a fifth or so of the total population. In these countries, complete integration of even more refugees is unrealistic. Other countries, including the United States, must share more of the burden.
IMPROVING BORDER security is vital. In 2015, Jordan’s border guards may receive over $10 million in U.S. funding. This is a valuable first step, but further emphasis on the border guards and others who may be the first line in stopping Islamic State incursions and managing refugee flows is vital for U.S. allies. Turkey has also moved slowly to prevent the passage of volunteers to the Islamic State and resisted U.S. and European pressure to step up efforts, often claiming it cannot secure its long border with Syria. The primary problem is political, not one of capacity, but Washington should make a show of helping Turkey on the capacity side with technological aid as a way of gaining Ankara’s goodwill and allowing it a face-saving way to explain its past laxity.
Neighboring countries will also need significant counterterrorism assistance, both to monitor and police the refugee camps and to prevent groups like the Islamic State from launching attacks. Money will talk, as the security services will need additional resources to meet the additional threat. The United States in 2015 provided roughly $1 billion in overt security aid to Jordan, and this figure may need to be increased. Some will also need more robust training programs, though several, notably those in Jordan and Saudi Arabia, are strong already. America’s own extensive intelligence efforts, particularly in high-tech fields like signals intelligence, will be valuable and should be shared with U.S. allies. The United States will also have to help coordinate intelligence efforts. The Islamic State and other groups are diffuse targets, and Washington needs to make sure that information gathered by one country is shared with relevant officials in others—a difficult task given the mutual suspicions that plague the neighborhood.
Counterterrorism efforts should prioritize the Syrian refugee community. The large numbers of angry and unemployed young men are natural targets of terrorist recruitment. Building up nonviolent community organizations and political bodies in the camp—and backing them against potentially violent groups—is vital. Better integration can also help with counterterrorism, as it will reduce the number of people in refugee camps where they can be more easily recruited.
To better oppose the Islamic State, Washington should step up its efforts to train the military forces of regional states, particularly Jordan and Lebanon but also Saudi Arabia. The militaries of Jordan and Saudi Arabia are not likely to melt away as the Iraqi army did in the face of the Islamic State, but better training and support will help them stand their ground. The United States should also develop contingency plans so it can rapidly deploy support to these countries to repel any incursions from the Islamic State or other jihadist groups.
THE UNITED STATES is working with regional allies to contain, and ideally roll back and defeat, the Islamic State. Washington has provided Bahrain, Jordan, Saudi Arabia and the United Arab Emirates with munitions, intelligence and coordinated airstrikes as those countries have joined U.S. forces in bombing Islamic State targets in Syria. The United States has also conducted military exercises and training for missions for improving internal security and counterinsurgency. U.S. strategy should also prioritize anti-Islamic State operations near border crossings to Turkey, Jordan and Lebanon to hinder Islamic State cross-border attacks.
Setbacks on the battlefield are likely to prove especially effective in reducing the risk of spillover related to the Islamic State. Part of the Islamic State’s appeal is that it is a winner and is successfully standing up to Iran, supposed apostate regimes and the United States. In addition, it taxes, extorts and otherwise extracts resources from the territory it controls. Pushing it back will both require it to focus resources on the immediate conflict and diminish its appeal abroad, though it may lash out with terrorism in revenge or to demonstrate its relevance.
Thwarting terrorism is likely to prove especially difficult in Lebanon, where Hezbollah—a terrorist organization as well as a guerrilla group and political movement—actually controls part of the government. Given the enmity between Hezbollah and the United States, the United States will not and should not give any support directly to Hezbollah. However, Washington has given Lebanon tens of millions in military financing, including guided antitank missiles and counterterrorism funding. Hezbollah would ostensibly benefit from a more direct U.S. effort to stamp out the Sunni jihadists in its midst, but the Lebanese group is not likely to accept a significant U.S. counterterrorism effort in Lebanon in general, believing (with some reason) that the United States would eventually like to turn it against Hezbollah itself. Any information sharing with the Lebanese military and security forces should be done with the recognition that information may also be leaked to Hezbollah.
THE SPREAD of radicalization is an especially tough problem. It is difficult for the United States and other outside actors to attenuate the radicalizing politics directly, especially given the deep unpopularity of the United States in much of the Muslim world. Much of the U.S. role will be working with regional governments to shore them up, bolstering their economies and otherwise trying to decrease discontent. The United States should also foster conflict resolution where possible in order to reduce the risk that limited grievances within these countries will spin out of control.
One dilemma concerns political reform. Long-term reform is vital to ensure stability as a way to prevent spillover. In the short term, however, reform can be destabilizing—as the fallout from the Arab Spring makes so clear. Pressure from spillover makes any reform project even less likely to succeed. Another sticky issue is that by enhancing the security services’ ability to fight terrorism and police refugee camps, the United States may also inadvertently be strengthening the forces tasked with suppressing democratic dissent in these countries. Finally, the collapse of the Arab Spring has left the reformist camp demoralized and with little popular support in most countries. Counterradicalization efforts cannot depend on political reform, at least in the short term.
In countries like Saudi Arabia and Jordan, counterradicalization will require pushing the regimes to reduce sectarian hatemongering. The Islamic State has successfully portrayed itself as the defender of the Sunni people against the Shia-Iranian menace. When Riyadh and others play up that menace, it indirectly benefits the Islamic State. Regimes should use their influence with local religious officials not only to condemn the Islamic State but also to counter the narrative it champions. Still, the U.S. role in fostering this will be indirect and limited at best.
A FINAL component of containing spillover is to put diplomatic pressure on allies like Turkey and Saudi Arabia—and coercive pressure on adversaries like Iran—to discourage them from intervening further in Iraq and Syria in ways that are opposed to U.S. goals. Turkey may share U.S. opposition to jihadist terrorism, but it sees fighting the Islamic State as less of a priority than changing the regime in Damascus. In addition, Ankara worries that Syria’s Kurds could strengthen Turkey’s own Kurdish movement.
The Gulf states themselves have often worked at cross-purposes, with Qatar backing Muslim Brotherhood-linked figures and more radical groups as Saudi Arabia backs others, often in concert with Jordan. The Obama administration has opposed much of this aid, believing that some of it went to more radical groups and that the funding of multiple factions was weakening overall unity. In October 2014, Vice President Joe Biden complained that “our allies in the region were our largest problem in Syria” and that they were contributing to a “proxy Sunni-Shia war.” There is progress. In 2015, Saudi Arabia, Qatar, Jordan and Turkey are working with the United States to train and equip several thousand troops to fight the Islamic State in Syria.
In addition, the United States wants to prevent interventions from creating a tit-for-tat spiral where a small deployment of, say, a dozen military advisors alarms the neighbors and escalates into large-scale conventional force deployments. At times this may involve offers of military sales, joint exercises and other shows of force that do little in practice but can reassure a jittery ally and highlight U.S. military power to any foes.
Some containment must also be done through proxy efforts in Iraq and Syria itself. The United States should bolster forces to fight groups like the Islamic State locally in order to consume the radicals’ energies and focus them at home. Ideally, this process would involve building local and national capacity to reduce the territorial holdings and eventually the capabilities of the radical groups. In Iraq, the United States has already gone down this road by working with Sunni tribes and the Kurdish peshmerga—initiatives that have grown in importance as the U.S. effort to rebuild the Iraqi army is moving fitfully at best. The United States needs to be sure that those facing the Islamic State directly are strong, so it should stop interfering with Kurdish efforts to sell oil and recognize that arms sales and military training will continue for the long term, even if this angers the central government in Baghdad. It should also relax vetting practices for the opposition in Syria (which would require both congressional action and some degree of bipartisan support given the political risks), recognizing that the price for greater opposition effectiveness will be direct or indirect U.S. aid to unsavory anti-Assad groups.
IN SYRIA, the United States faces another challenge. Washington is engaged in military and other efforts to degrade and defeat the Islamic State, yet it is also opposed to the Assad regime. Weakening the Islamic State does not solve the spillover problem: the continued ferocity of the Syrian war will ensure that it remains acute.
So far Washington has failed to persuade Tehran to end or reduce its support for Damascus. Obama administration officials have criticized Iran’s role and excluded it from peace negotiations because Tehran does not appear willing to support concessions by the Assad government. Indeed, when the Assad regime stumbles, Iran helps pick it up. In 2015, for example, Iran sent more of its own forces and its proxies into Syria after the Assad regime lost territory to a coalition of rebel groups. The United States should continue to press Iran to cut support but not expect any significant change.
The United States has provided Saudi Arabia with munitions, intelligence and aerial-refueling assistance for its campaign against Houthi rebels in Yemen. Such aid is an easy “gimme” to Saudi Arabia. However, the Saudi intervention has little chance of significant long-term success and may be worsening Yemen’s civil war. Washington should try to discourage the kingdom escalating and ideally to reduce its intervention there. At the very least, the United States should push Saudi Arabia for more coordination in Iraq and Syria as a price for this cooperation.
In general, the United States should use arms sales and other forms of influence to reassure allies and gain influence over their decisions. At times these systems do little for counterterrorism or other shared threats: funding to Jordan, for example, helps its air force purchase advanced air-to-air missiles that do little to help Jordan against any of its current challengers. Still, systems that require U.S. assistance for logistics are valuable, as they give the United States a de facto veto over the use of these weapons and often the sustainability of a broader intervention.
IF CONTAINMENT works, it would prevent the conflagration that is consuming Iraq and has consumed Syria from inflaming violence in neighboring states and make neighbors less likely to escalate their involvement in Iraq. Indeed, it is possible that countries like Saudi Arabia and Iran might become less involved than they are now if they recognize that the fighting in Iraq is less likely to affect their interests directly. Containment also has humanitarian benefits: though it may seem callous to let existing fires burn, successful containment means the conflicts will be less bloody and less likely to spread. Refugees also will receive better care. Finally, successful containment will help manage the terrorism threat.
Containment is also far less costly than more aggressive options like direct intervention or partition. Containment does not demand a large-scale military presence, and even a significant aid package is far cheaper than deploying military forces. Diplomatically it is also less burdensome, though it would involve constant efforts to reassure and cajole allies and pressure adversaries.
Yet despite its considerable potential, many of the benefits of containment will be difficult to achieve. All of the governments in the region are skeptical of the U.S. commitment to their security. The United States and Saudi Arabia are at odds over the Iran nuclear deal, as well as over what Riyadh sees as U.S. vacillation in Syria and the abandonment of long-standing allies during the Arab Spring. The Obama administration’s desire to reduce the U.S. role in the Middle East has led other countries to share the Saudis’ skepticism. U.S. efforts to coordinate allied activity and to shape Iranian behavior are particularly unlikely to succeed.
Containment, moreover, means playing defense—it doesn’t solve any of the current problems, even if it stops some new ones from arising. The tremendous suffering of the civil wars will not end. The war may burn out on its own, but the United States would have little influence over who is the victor, and the possibilities include jihadists or the Assad regime, as well as the less loathsome but not particularly pleasant assortment of thuggish leaders usually found in the Middle East. In addition, the regional and local pressure waves the civil wars generate are often stronger than what the United States can do in response.
Both before and after the U.S. troop withdrawal from Iraq, Washington tried to use its diplomatic and moral power to convince the Iraqi government to be more inclusive and to ensure that the Iraqi military remained effective: both failed disastrously, and that was before the resumption of civil war raised the stakes even higher and made the cost of this failure more dear. Because it is difficult for containment to work, its low cost may be illusory, and indeed it may mean the problem metastasizes and the United States ends up paying a higher cost should it decide to take more aggressive steps in the future.
Yet in the end, containment is a necessity if the United States does not want to increase the scope and scale of its intervention. Accepting this, and acting accordingly, will check the damage to American interests.
Daniel Byman is a professor at the School of Foreign Service at Georgetown University and a senior fellow at the Center for Middle East Policy at the Brookings Institution. His latest book is Al Qaeda, the Islamic State, and the Global Jihadist Movement: What Everyone Needs to Know (Oxford, 2015). He tweets at @dbyman.