United Nations Security Council Resolution 2178, adopted on September 24 after a debate involving dozens of world leaders, including United States President Barack Obama, is legally and strategically significant, reflecting the magnitude of the danger posed by the Islamic State of Iraq and the Levant (ISIL). Mirroring the complex dynamics of the threat itself, the resolution has many significant components, including encouragement of states to increase their efforts to counter violent extremism; changes to the UN institutions charged with counterterrorism policy; and calls for enhanced intelligence sharing among member states. But the most consequential requirements of the resolution are those designed to stem the flow of foreign fighters streaming to the zone of instability in the Fertile Crescent. The mandates of the resolution are innovative, and its structure is modeled after UN Security Council Resolution 1373. UNSCR 1373 was adopted in the weeks after 9/11 and imposed on states an obligation to criminalize the provision of financial support to terrorist groups, and to make substantial efforts to effectuate the resolution’s requirements.

The international fight against terrorist financing has seen significant successes. But a similar effort to curtail the flow of foreign fighters may struggle to achieve its stated aims for the same reasons a Security Council mandate to crack down on the phenomenon was necessary in the first place: Many of the most relevant states lack the political will or the capacity to prevent the flow of fighters to Iraq and Syria.

If Resolution 2178 is to work as hoped, therefore, the US government and its allies in the Security Council must follow the same blueprint that has led to important achievements in the terrorism financing context, and must follow up the resolution with a mix of three diplomatic tools: 1) Consistent pressure at the highest levels designed to overcome domestic political obstacles to robust enforcement of UNSCR 2178 in states that are the origin or transit points for foreign fighters; 2) Sustained information sharing to help states with less effective intelligence services identify networks of facilitators operating in their countries; and 3) Working-level assistance, including by UN organs like the Counterterrorism Executive Directorate, to build effective border control and interdiction processes. Only by doing so will the resolution live up to its promise.

Before analyzing the structure of the resolution and how it fits into the architecture of transnational counterterrorism regulation, it is helpful to understand the strategic context. The Islamic State in Iraq and the Levant roared onto the international scene earlier this summer, when it took control of significant portions of Northern Iraq. But the group, a successor to al-Qaida in Iraq, started to pose a significant threat to the stability of the country early this year, when, operating from its secure rear in Syria and aided by fighters drawn from nearly half the member states of the UN, ISIL took control of the predominantly Sunni city of Fallujah. Since then, the amount of territory ISIL came to control increased dramatically until the United States intervened with air strikes this past summer, which, along with valiant efforts by Kurdish fighters on the ground, checked the group’s rapid advance.

The US government has led a truly transnational effort to contain and roll back this quintessentially transnational threat. US Secretary of State John Kerry has expended significant efforts in the last several weeks to knit together a broad coalition of over sixty countries dedicated to fighting ISIL. Members of the group include Arab countries like Saudi Arabia, Bahrain, and the UAE, which have conducted air strikes alongside US and European partner nations. And those committed to both use force and contribute more broadly to the effort include France, Germany, and Canada. But while military force may be necessary to degrade “and ultimately destroy” ISIL, it will not be sufficient. And so the coalition has banded together to methodically dismantle the ecosystem that sustains ISIL by curtailing its sources of financial support (including donations by individuals and the sale of oil and petroleum products), striking the group kinetically, and starving it of the recruits it needs to succeed militarily.

It is in this context that we should see the Foreign Fighter resolution: As part of a broad-based, holistic, multinational approach to arresting and then reversing the group’s gains.

But the resolution also emphasizes foreign fighters because of the unique threat that such fighters pose to Western countries. Indeed, the EU’s top counterterrorism official recently estimated that 3,000 Europeans had been to fight in Iraq and Syria, and Matthew Olsen, the Director of the National Counterterrorism Center, recently estimated that over 100 Americans had gone to fight there out of a total foreign fighter population that exceeded 12,000 people. These individuals have Western passports and can return to their home countries easily to commit terrorist attacks.

The threat of western citizens returning home to commit attacks is not merely hypothetical. In May of this year, a 29-year-old French citizen of Algerian descent committed a terrorist attack at the Jewish Museum in Brussels, having recently returned from Syria where he had fought alongside ISIL. The same month, a 22-year-old American detonated himself in a suicide truck bombing in Syria, demonstrating a willingness on the part of Western recruits to commit serious terrorist attacks. Western counterterrorism officials fear that such attacks, involving battle-hardened jihadis returning from the fight in Iraq and Syria, will only accelerate with time, and so felt a strong imperative to generate an international consensus (and the accompanying legal instruments) to make progress against the foreign fighter phenomenon.

Legally, the resolution builds on the model of transnational counterterrorism regulation embodied in UNSCR 1373, which required all member states to criminalize the provision of financial support to terrorist groups. In adopting this structure, the international community appears to have moved even farther down a path that diverges from the treaty-based global counterterrorism regime that predominated before 9/11. While there is no single international treaty banning terrorism, there have been many treaties adopted since the 1960s that banned specific terrorist acts. Thus, in 1970 the international community adopted the Hague Convention for the Suppression of the Unlawful Seizure of Aircraft; in 1979 a treaty was adopted forbidding the taking of hostages; and in 1997 a convention was adopted to bar terrorist bombings.

UNSCR 1373 introduced a process by which, instead of going through the long and sometimes inconclusive procedure of treaty-drafting (which, for example, has plagued attempts to conclude a Comprehensive Convention on International Terrorism), the Security Council can impose binding obligations in response to rapidly evolving international conditions through the vehicle of Chapter VII resolutions. Thus, just as UNSCR 1373 required states to adopt domestic legal instruments banning terrorist financing, UNSCR 2178 requires states to take specific and concrete steps to clamp down on the movement of foreign fighters from and through their territory.

But while Resolution 2178 was adopted rapidly, the true test will come in its implementation. The analogy to the fight against terrorist financing is again instructive. In this context, countries like Qatar have formally adopted the requisite legal instruments to diminish the flow of funds to terrorist groups have often also failed to robustly implement those tools, and as a consequence have become permissive environments in which a wide range of terrorist groups are able to raise money. So too in this case, must countries like Turkey and other Gulf states tighten their border controls, enhance cooperation with each other and with Western intelligence services, and integrate more readily with international agencies like the UN and INTERPOL in order to prevent (predominantly) young men from joining the fight in Syria and Iraq.

And this is where the true value of UNSCR 2178 will be realized, as the resolution will serve as a tool to encourage countries that lack the capabilities or political will to take aggressive action against foreign fighters. Specifically, effective implementation will require a political decision at the highest levels of government to devote the resources necessary and direct the activities of security services to address the foreign fighter problem. As Western governments and the UN engage on this issue, they will be able to point to binding international legal obligations to take action, which will enable jurisdictions that are the source or transit points for foreign fighters to overcome potential domestic political resistance to doing so. It will also facilitate the sustained provision of resources and technical expertise from countries that have it to those that need it to better prevent foreign fighters from transiting or departing.

UNSCR 2178 in many respects instantiates the indefinite struggle against al-Qaida and affiliated groups that President Obama vowed to end as recently as May 2013. It envisions a sustained multi-dimensional campaign to degrade and destroy a collection of brutal terrorist groups in the fragile and failing states in the Middle East. It provides a vehicle to engender expanded political commitment to controlling the transit of foreign fighters, and a mechanism to provide technical assistance towards that same end. It also further solidifies a mode of transnational legal regulation of counterterrorism that has shifted away from a treaty-based model, and instead embraces a Security Council-led process that quickly can adapt to the evolving needs of the international community. The resolution was an important first step, but the hardest work—to implement it effectively—has just begun.