The case of Shamima Begum will be seen as part of a wider dilemma for Western governments about what to do with people who want to return now that ISIS' control of swaths of Iraq and Syria has all but dissolved.
"I'm not the same silly little 15-year-old schoolgirl who ran away from Bethnal Green four years ago," she told The Times, referring to her neighborhood in East London. "And I don't regret coming here."
Begum, who told the Times she is nine months pregnant, is like thousands of people all over the world who were lured by ISIS propaganda to join the militant movement then marauding the Middle East and beyond.
Once her trio arrived in Syria, they joined a fourth friend already there who also married an ISIS fighter, Begum said. One of the girls was killed in an airstrike, and the other two elected to stay on for what could be the militants' final stand in a battle at the town of Baghuz, near the Iraqi border, she said.
It is not clear whether the girls were ever combatants, no how deep their support for the group went. But now that ISIS has lost almost all of its territory, Western intelligence services worry about what to do with these so-called foreign fighters and their families once they return home.
The fear is that they could try to mount attacks once back in their homelands, or at least stir up support for a cause they may claim to have renounced. Attempting to monitor them represents a huge burden for governments.
I don't imagine the Foreign Office will be rushing into Syria to try and get hold of her.
"Somebody who has spent a lot of time in the caliphate is likely to be radicalized, and women are as capable of committing terrorist acts as men," said NBC News security analyst Duncan Gardham. "It may be a difficult task to make sure she is not radicalized and ensure that she's not a threat."
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The stereotypical image of foreign fighter tends to be male, like Albert Berisha, a Kosovar man interviewed by NBC News last year who traveled to Syria to fight the government of Bashar al Assad and claims he accidentally fell in with an ISIS unit.
Prosecuting returnees who have committed crimes with ISIS, however, raises issues about where to incarcerate them — without risking radicalizing other inmates — and what to do with them upon their release, Shiraz Maher, director of the International Centre for the Study of Radicalisation and Political Violence, at Kings College London, said in a tweet thread on Thursday.
Again, it's not clear how deep Begum's involvement with ISIS went, but she should be treated no differently, in terms of the potential threat she poses the U.K., because she is pregnant, Gardham said.
Last year, two sisters and their mother were jailed as part of an all-female terror cell that wanted to carry out an attack on British soil. In 2016, a British woman, Tareena Shakil, 26, was jailed for six years for taking her young son to Syria and joining ISIS.
If there is evidence, Begum could be arrested for joining a banned terror group, or for merely deliberately staying in what the British government calls a "designated area" — essentially a war zone like Syria.
Even if she is classified as a noncombatant, the importance of her merely being in Syria should not be dismissed, Maher said.
Their presence in ISIS territory alone represented "a type of moral and propaganda victory for the group," he tweeted. "Don't underestimate how important that was."
But whatever you think, there is very little public sympathy for those who voluntarily migrated to Islamic State. That strengthens the hand of our governments who are adopting a position of passivity towards this problem. They’re happy to embrace the omission. 27/
Her legal status might be the easy bit. Morally, there has already been a wide public disagreement in Britain about whether Begum can and should be rehabilitated back into society.
In 2015, she was widely portrayed as the 15-year-old victim of online brainwashing, someone who needed to be saved from the clutches of a murderous death-cult.
Now, her unapologetic interview in The Times has led many to say that she should be left to her own fate.
Security minister Ben Wallace pointed out that as a British citizen Begum had the right to return to the U.K. However he said she would at least be investigated by counterterror police and suggested that the public’s safety would take priority.
"I'm not putting at risk British people's lives to go and look for terrorists or former terrorists in a failed state," he said on BBC radio early Thursday.
Officially, it is U.K. policy to tell British women in this situation to get themselves to the nearest consulate to be repatriated. Unofficially, the government "would rather they did not come back," Gardham said. "They don't want jihadi brides back and they don't want jihadis back."
This stands in contrast to the approach of the U.S., which has been more likely to take on and prosecute alleged terrorists, Gardham added.
Sir Mark Rowley, former head of British counterterrorism policing, agrees the U.K. will likely display a passive attitude toward Begum.
"I don't imagine the Foreign Office will be rushing into Syria to try and get hold of her," he told BBC radio Thursday morning.
If Begum were to return and be arrested, the problems would not stop there.
"I think actually the biggest challenge would be if she did come back," Sir Peter Fahy, the former head of Britain's counterterrorism program Prevent, told BBC radio.
"How the local police would keep her safe and how it would be ensured she would not be some sort of lightning rod," he added, "both for right-wing extremists and Islamic extremists, and that she wouldn't somehow try to justify her position and what she did."
Alexander Smith is a senior reporter for NBC News Digital based in London.