One of the biggest challenges in the war against terrorism has been the failure to prosecute its supporters

Making an example of Shamima Begum through proper legal channels would have shown no one can get away with backing a violent cult

Iraqi men bury the victims of a suspected ISIS attack in the cemetery in Najaf. Reuters

Earlier this month, the Pentagon issued a warning that ISIS militants are regrouping and that they could regain control of territory within six to 12 months, if significant action is not taken to counter their activities.

In a quarterly report intended to track the progress made against the extremist group, the US military warned that ISIS is consolidating at a faster pace in Iraq than in Syria, where, two years after declaring victory, the government struggles to provide basic housing and health services for its people. The potent mix of security vacuums, a proliferation of arms, large numbers of unemployed men – whose only skill might be fighting – and long-held grievances still exists.

And yet, the impact of ISIS is not restricted to Iraq and Syria, nor to the domestic political situations of each. The militant group’s ability to attract thousands of foreign fighters ensured it had far greater reach than other militant groups. Late in 2014, the CIA estimated that there were 15,000 foreign fighters in ISIS ranks, with several thousand from Europe and hundreds from North America, either fighting or choosing to live in ISIS-held territories. Huge efforts were made to profile those fighters and to understand what could possibly drive young Europeans or Americans to pick up arms for ISIS. Even more baffling was the decision of dozens of young women to head to Iraq and Syria to support ISIS, many of them becoming brides for the militants.

There is an undeniable curiosity about what drives ISIS recruits and supporters. In the past few weeks, captured members of the extremist group have been getting hours of airtime, as international journalists have been given rare access to interview them. The Syrian Democratic Forces holding ISIS fighters are granting interviews to journalists, in part to force the governments of foreigners to take them back. The SDF's fears are that an imminent US withdrawal or reduction of troops will allow these fighters to escape. So far, western governments have declared themselves unwilling to take back fighters and supporters who chose to join ISIS and renounce their own systems of government. This is an abdication of responsibility that cannot be ignored.

Shamima Begum is a case in point. Begum fled the UK to join ISIS and has put a renewed spotlight on the teenagers who were recruited to the ranks of the militant group. Just 15 years old when she arrived in Syria, Begum married an ISIS fighter soon after and is now appealing to return to the UK. She has tried to manipulate media attention to get there. The British government's response of stripping her of British citizenship has been telling. Not wanting to deal with this crisis, the UK's Home Office has moved to revoke the citizenship a British-born woman rather than seeking to try her.

The frenzy of commentary on the stripping of Begum's citizenship is warranted. The precedent it sets of revoking the passports of children of immigrants threatens to create a two-tier citizenry within the UK, where descendants of immigrants can be seen as not really belonging. At a time when hate crimes are on the rise and immigration is used as a political football, this is a worrying development. It was wrong of the UK government to assume that Begum, who has never visited Bangladesh, should be sent to her parents' country of birth. Her son, born to a British mother, should mean he has rights as a British citizen but with her current stateless position, an innocent newborn is facing an even bleaker future.

In an interview with The National, the UK's Minister of State for the Middle East Alistair Burt said Begum would face a fair trial in the UK, if she made her own way back to the country. And yet no real effort is being made to have her face court, despite new laws being passed by Parliament last week to prepare for such cases of returning ISIS recruits. The Counter-Terrorism and Border Security Act increases sentencing powers for supporting proscribed organisations and taking part in any terrorist-related activity.

The new legislation undoubtedly was brought in because one the biggest challenges in the war against terrorism since September 11, 2001, has been the international failure of judicial systems to try those accused of supporting it. From Guantanamo Bay detention camp housing Al Qaeda members to thousands of detainees held without trial in Iraq and Afghanistan, international actors have not met the challenge of championing justice through proper legal channels. Defeating ISIS and terrorist ideologies requires upholding laws and due process.

Making an example of Begum is important. No one should be under the illusion that they can get away with supporting the mass murder of innocent civilians and the imposition of a violent cult. Defeating the ideology of ISIS requires casting a strong light on those who championed the terror group and now face its decline. Although Begum has not voiced remorse, seeing her, and others like her, on the decline is a significant moment in marking the defeat of ISIS – at least for the time being. However, what is more important is to present a coherent and fair judicial process to try those accused of crimes against humanity – because that is what Begum and all those who stood with ISIS are really guilty of.