It is hard to summon much sympathy for the thousands of ISIS fighters and their dependants who now find themselves languishing in Kurdish-run detention camps following the final collapse of their so-called caliphate. With the exception of the children who never asked to be born into such depravity, these are the people who are responsible for creating and sustaining a movement that visited untold misery upon those unfortunate enough to find themselves subject to the group’s reign of terror across large tracts of northern Iraq and Syria. Moreover, many of the fighters now in the custody of the Kurdish-led Syrian Democratic Forces (SDF) – the western backed group that was at the vanguard of the final push to <a href="http://www.thenational.ae/world/mena/baghouz-last-bastion-of-isis-territory-falls-in-syria-1.840330">destroy the last remnants</a> of the caliphate in the Syrian border village of Baghouz – are unapologetic about their support for ISIS. Whether, fearing death, they opted to surrender, or were taken captive as the SDF and its western backers intensified the military effort to flush out the last pockets of resistance, the majority of those now in captivity have made it abundantly clear that, given the chance, they remain committed to ISIS’s murderous doctrine. The temptation then, especially in the West, is to abandon them to their fate, particularly the estimated 1,000 foreign fighters now in captivity, who left their homes to join the caliphate. Britain, for example, is among several European states that believes the best way to deal with surviving ISIS members is to strip them of their citizenship, thereby denying them the right to return home. This approach has been highlighted by the high-profile case of Shamima Begum and the attempts of the British Home Secretary Sajid Javid to strip her of citizenship. The argument advanced by British and other European security chiefs for subjecting ISIS veterans to such measures is that, if they were allowed to return, they might help to further the cause of Islamist extremism. This concern is not entirely without merit. For example, many of the detainees held at the US Guantanamo Bay detention facility, whose release was only secured following an outcry from western politicians, ended up being involved in committing further acts of terrorism. Indeed, documents recently collected after the fall of Baghouz reveal that, for all its recent setbacks, ISIS remains <a href="http://www.thenational.ae/opinion/editorial/isis-is-defeated-but-its-ideology-is-not-1.840943">committed to waging war</a> by any means possible, which includes carrying out a wave of terrorist attacks in Europe. The so-called ISIS files, a collection of documents obtained from ISIS fighters, which have been published in <em>The Sunday Times</em>, reveal that the organisation aims to set up a "department of operations in Europe" that would provide support to ISIS members already living there, enabling them to operate so-called "crocodile cell" assassination squads, whose mission would be to "kill the enemies of God". The obvious conclusion to draw, then, is that, while ISIS may have lost its caliphate, it has lost none of its appetite for committing further atrocities around the globe, a consideration world leaders would be well-advised to take on board as they reflect on their next moves. Simply abrogating responsibility for the problem, and leaving the Kurdish-led administration in the north-east of Syria to resolve the fate of the ISIS captives, is not the solution. For a start, by their own admission, the Kurds simply cannot cope with the sheer volume of ISIS fighters and their associates that they now have in detention. Moreover, given the SDF fought to help western powers, such as the US and Britain achieve their ultimate goal of destroying the caliphate, the West has a moral obligation to provide them with all the assistance they need. Ideally, this would involve setting up an international tribunal, similar to those that dealt with war crimes committed during the Balkans conflicts and the 1994 Rwandan genocide, to deal with those involved in the orgy of violence that was committed by ISIS fighters. This is certainly the preferred option of Abdulkerim Umer, a senior official with the Kurdish-led administration in northern Syria, who has called for the establishment of “a special international tribunal in north-east Syria to prosecute terrorists” that will ensure the trials are “conducted fairly and in accordance with international law and human rights covenants and charters”. Setting up such a body, though, is <a href="https://www.thenational.ae/opinion/editorial/the-world-must-bring-militants-to-justice-1.842060">more easily said than done</a>. For a start, the Kurdish-controlled enclave in Syria remains disputed territory, and its status will remain unresolved unless the West can be persuaded to back peace negotiations over the post-conflict resolution of Syria, which for the moment seems unlikely. The legal basis for setting up a tribunal in the Kurdish enclave would also face challenges, as neither Syria nor Iraq are signatories to the 2002 Rome Statute that established the International Criminal Court. Faced with these challenges, the most obvious solution therefore would be for all those countries who have been involved in the long-running campaign to defeat ISIS to accept they have a moral obligation to deal with the aftermath of the caliphate. For countries such as Britain, this means allowing its citizens who joined ISIS to return home and face the consequences of their actions. This is certainly the intention of James Jeffrey, the US envoy for Syria, who earlier this week said that “getting countries to take back their own foreign terrorist fighters” remained his main priority. Otherwise the military campaign to destroy the caliphate could prove to be a Pyrrhic victory, one where the caliphate is defeated, but its supporters are not held to account for their actions. <em>Con Coughlin is the Daily Telegraph’s defence and foreign affairs editor</em>