Exploited victim or unrepentant villain? It’s impossible to determine the truth about Shamima Begum, the 19-year-old who left Bethnal Green in London when she was 15 to join Islamic State, from a single newspaper interview. And it shouldn’t be hard to acknowledge that more than one interpretation of her story might contain a ring of accuracy.

Begum is undoubtedly vulnerable. She was groomed online at the age of 15; married off, albeit willingly, to a jihadist fighter while still a child just 10 days after arriving in Raqqa, Syria; in recent months, she has lost two infants to malnutrition and inadequate healthcare. Heavily pregnant with her third child, she says: “I’ll do anything required just to be able to come home and live quietly with my child.”

We as observers may feel at once a disconcerting mix of compassion for her suffering … and disgust for her views

But it is also true that Begum travelled to Syria to join one of the world’s most brutal terrorist organisations, fully aware of the terrible atrocities it commits, including the genocide of Yazidis in Iraq. It is impossible not to feel shock at her apparent lack of remorse; her claim not to be fazed at the sight of a severed head in a bin; her response to videos of British hostages being beheaded: “Were these not journalists and stuff that were caught spying?” She may or may not have committed or abetted crimes in the name of Isis; her networks, knowledge and beliefs may or may not make her a grave security threat wherever she lives in the world.

We as observers may feel at once a disconcerting mix of compassion for her suffering, though it pales against that for Isis’s victims, and disgust for her views. But from ministers we have the right to expect more: a cool-headed assessment of how the UK must act based on its obligations under the rule of law and its duty to keep British citizens safe.

On this, they have failed. The home secretary, Sajid Javid, said last week he would not hesitate to prevent her return to the UK. This is unlikely to be possible legally: Begum remains a British citizen and the Geneva conventions proscribe governments from making their citizens stateless.

But preventing Begum’s return is wholly the wrong thing to do, even if it were possible. The only purpose it serves is virtue-signalling how tough Javid is on radicalised teenagers sympathetic to terrorism.

The correct approach to British citizens who hold abhorrent views … is not to abandon our values, or to junk due process

On security grounds alone, she should be brought home. British citizens who have travelled out to fight for or support Isis pose a security risk. Radicalised Europeans who have returned from Syria have committed terrorist attacks on European soil, including the Paris attacks in November 2015. Begum was radicalised here as a child. It is Britain’s responsibility to manage any consequential risks. Leave her in Syria and she may turn up, undetected, in the UK, via established smuggling routes, or do untold damage in radicalising others against Britain and the west. Bring her back through official channels and she can be questioned by the security services, held to account for any crimes she may have committed, to the extent that the evidence allows, and put through a deradicalisation programme.

Even more importantly, Begum must be allowed into Britain simply because it is what the rule of law demands. She is a British citizen, about to give birth to an innocent child who will be a British citizen by descent. The correct approach to British citizens who hold the abhorrent views of Begum is not to abandon our values or to junk due process. It is not to deprive a British citizen of their statehood, in contravention of international law. It is to bring her back to the UK and for her to be charged and face trial to the extent that the evidence allows. It is for the justice system, not for MPs and a social media mob, to determine the extent to which she is a victim or a perpetrator. And it is for the intelligence services to determine the extent to which she is a security risk.

There are risks in this approach. Only about one in 10 of 400 or so British returnees from Syria have been successfully prosecuted, in some cases because there are restrictions on the admissibility of evidence collected from battle sites. Begum may be considered a security threat, but may not have committed crimes beyond supporting Isis, or the evidence for crimes of which she is suspected may be too weak to secure a conviction. But these are risks that can be best managed in Britain. At the very least, if Begum is deemed a security threat, she can be monitored and compelled to take part in a deradicalisation programme. The risks of leaving British citizens who have joined Isis in the Middle East to their own devices, out of a childish, wrong-headed instinct that they deserve no better, are greater still.

Begum is also a test case for the British government’s approach to the hundreds of British fighters and supporters of Isis who are alive in Syria today. Like her, these individuals should be gradually repatriated in a controlled fashion and interrogated and, where possible, charged with any crimes they may have committed.

Begum may have been groomed as a 15-year-old, but her support for a terrorist organisation that has committed unspeakable atrocities means she has much to atone for on her return to the UK. Perhaps she will, perhaps she won’t. Perhaps the threat from Isis will never be fully extinguished. But one thing is certain: it will never happen if we compromise the liberal values and abandon the rule of law that set us apart from the enemies who hate us.