The videos depicting beheadings of Western civilians by the Islamic State of Iraq and Syria (ISIS) have shocked audiences worldwide. But perhaps more surprising is something more mundane: the distinctly British accent of the English-speaking, knife-wielding militant.

Dubbed “Jihadi John” by the Western media, the cloaked figure highlights a troubling trend: Thousands of foreigners, many of them Westerners, are flocking to Iraq and Syria to join ranks with ISIS, al-Nusrah Front, and other al-Qaeda splinter groups.

On Wednesday, U.S. President Barack Obama will chair a special session of the UN Security Council focused exclusively on the threat posed by foreign fighters. He is expected to table an ambitious resolution dedicated to countering this scourge. The resolution, if it passes, is a critical first step. But the broader effort will require two far more difficult undertakings: commitment from allies in the Middle East and a sustained effort to better integrate Muslim communities in Western countries.

Invoking Chapter VII of the UN Charter, which empowers the Security Council to impose binding provisions on all UN member states, the draft resolution legally requires that all governments:

prevent and suppress the recruiting, organizing, transporting or equipping of individuals who travel to a State other than their States of residence or nationality for the purpose of the perpetration, planning, or preparation of, or participation in, terrorist acts or the providing or receiving of terrorist training, and the financing of their travel and of their activities.

Dense though it may be, this paragraph marks the Security Council’s first attempt to legally define a “foreign terrorist fighter,” a category absent from existing UN counterterrorism agreements. Among other provisions, the resolution calls on UN member states to strengthen border security and improve international intelligence sharing, including airline passenger information, to detect the movement of individuals targeted by UN sanctions. The resolution also mandates that the UN Counterterrorism Committee (CTC), established in the wake of September 11, to identify “gaps” in UN member states’ capacities to prevent foreign fighters from traveling abroad.

(Related: Meet the Other Terror Group in Syria That Could Actually Threaten the US)

Despite the sudden flurry of attention surrounding the identities of ISIS militants, the foreign fighter phenomenon is hardly new. For decades, Islamist insurgent groups have targeted foreigners for recruitment. From Afghanistan to Chechnya to Somalia, foreign combatants have played decisive roles in conflicts across the Muslim world since the 1980s. Abdullah Azzam, a Palestinian scholar of Islamic jurisprudence, is widely regarded as the “father” of global jihad. Following the Soviet invasion of Afghanistan, Azzam mobilized Muslim fighters from around the world to expel the communists, building a network of radicalized, stateless militants along the way. Despite his assassination in 1989, Azzam’s legacy endures.

The movement of foreign fighters across borders is an inherently transnational phenomenon. As such, tackling the threat they pose requires global coordination. The Obama administration’s Security Council resolution on foreign fighters is thus a welcome development. Until now, the foreign fighter problem has spurred little action in multilateral settings.

What’s changed? The sheer size of the problem, for one. Under the banner of jihad, foreigners are journeying to Iraq and Syria in unprecedented numbers. The CIA estimates that ISIS is between 20,000 and 31,500 men (and women) strong. Half of its members are non-Iraqis and Syrians, hailing from more than eighty countries. They include hordes of Jordanians, Tunisians, and Saudis. But an estimated 2,000 are of Western origin, including hundreds of British, French, Belgian, Dutch, and Australian nationals. U.S. Secretary of Defense Chuck Hagel has said that at least one hundred U.S. citizens have joined various rebel groups in Iraq and Syria, including a dozen fighting with ISIS.

Another new variable is social media. Unlike conflicts in decades past, extremist rebel groups now exploit Twitter, YouTube, and Facebook to disseminate propaganda, contact recruits, and maintain a global network of sympathizers on a scale that would have been unimaginable to Abdullah Azzam. Initially, ISIS, al-Nusrah Front, and other groups attracted foreigners by invoking solidarity among Sunni Muslims worldwide in the struggle against Bashar al-Assad, who belongs to the Alawite sect of Islam. It worked. Sunnis descended on Syria to defend their co-religionists. The advent of social media platforms means that recruiters need not rely on word of mouth, letters, or third parties to broadcast their calls to arms; they can simply reach out to young prospective fighters directly.

The rising tide of foreign fighters poses dangers both locally and globally. Compared to their local counterparts, foreign fighters tend to be more ideological, brutal, and willing to commit atrocities, all of which exacerbate sectarian tensions, further radicalize parties, and extend conflicts. But U.S. government officials also worry that passport-holding Westerners waging jihad abroad are likely to return to carry out attacks against the homeland. Foreign fighters “often return home radicalized by their experiences,” warns Samantha Power, U.S. ambassador to the UN. Matt Olsen, director of the U.S. National Counterterrorism Center, also cautions that foreign fighters “may eventually return to their home countries battle-hardened, radicalized and determined to attack us.”

(Read More: The Islamic State Threat May Be Extending to the Asia-Pacific)

The proposed U.S. resolution will undoubtedly pass the Security Council, with full support from Russia and China. This may seem surprising, given how their obstructionism has repeatedly paralyzed the Security Council vis-à-vis the regime of Bashar al-Assad. The about-face reflects the vulnerability of both countries to transnational jihad. For two decades, Moscow has been combating extremists in Russia’s predominantly Muslim provinces in the North Caucasus, particularly in Chechnya and Dagestan. The December 2013 bombing in the southern Russian city of Volgograd, in the run-up to the Sochi Olympics, provides just one example. Meanwhile, Chinese authorities face continued unrest in the western province of Xinjiang, where longstanding tensions between the majority Han and the indigenous Muslim Uighur populations regularly erupt into violence.

Scratch a bit deeper, however, and this ostensible consensus in the Security Council on destroying today’s most powerful machine of foreign fighters begins to wear thin. President Obama, of course, has declared his determination to strike at ISIS wherever it operates, including not only Iraq but Syria. Vladimir Putin, however, maintains strong support for Assad, and opposes any strikes on Syrian territory in the absence of a UN imprimatur. U.S. interests also diverge from important regional players, including those of Turkey—Washington’s NATO ally and fellow co-chair of the Global Counterterrorism Forum. Turkey, whose porous borders with Syria have served as the main conduit for foreign fighters into Syria, is loath to join the U.S.-led coalition against ISIS. Like the regime in Qatar, which has actively sponsored some of the most radical jihadi groups in Syria, Turkish President Recep Tayyip Erdogan is preoccupied with deposing the Assad regime and will thus likely continue to allow future Syrian rebels to freely cross the Turkish-Syrian border.

A related quandary is the continued failure of the United Nations to formulate a consensus definition of “terrorism.” When it comes to this Security Council resolution, one state’s “foreign fighter” may be another state’s “freedom fighter.”

Moreover, the draft U.S. resolution presumes that countries have not been stopping foreign fighters because they lack the capacity to do so. (It’s precisely for this reason that the resolution asks the CTC to report on capacity gaps in UN member states.) In practice, the failure to interdict foreign fighters derives as much from their lack of commitment as from their lack of capacity.

Finally, the ease with which ISIS has recruited foreigners to its ranks points to a broader issue: the challenge of cultivating a sense of belonging among often marginalized diaspora populations—in this case, of Muslim immigrants—in Western countries. For the thousands of young men and women who abandoned Western countries to take up arms with ISIS, the pull of transnational identity—and the prospect of establishing a so-called “Islamic State”—proved more alluring than the obligations of citizenship.

This week’s Security Council resolution begins the important work of constructing a global framework against foreign fighters and prosecuting those who slip through the cracks. But for the West, the greater challenge will be fostering a sense of civic identity among minority populations susceptible to the false promises of far-flung fundamentalists.

This post appears courtesy of CFR.org.