London. A woman who traveled to Syria as a teenager to join the Islamic State group lost her appeal Friday against the British government's decision to revoke her UK citizenship, with judges saying that it wasn't for them to rule on whether it was “harsh” to do so.

Shamima Begum, who is now 24, was 15 when she and two other girls fled from London in February 2015 to marry IS fighters in Syria at a time when the group’s online recruitment program lured many impressionable young people to its self-proclaimed caliphate. Begum married a Dutch man fighting for IS and had three children, who all died.

Authorities withdrew her British citizenship soon after she surfaced in a Syrian refugee camp in 2019, where she has been ever since. Last year, Begum lost her appeal against the decision at the Special Immigration Appeals Commission, a tribunal that hears challenges to decisions to remove someone’s British citizenship on national security grounds.

Her lawyers brought a further bid to overturn that decision at the Court of Appeal, with Britain's Home Office opposing the challenge.

All three judges dismissed her case.

In relaying the ruling, Chief Justice Sue Carr said it wasn't the court's job to decide whether the decision to strip Begum of her British citizenship was “harsh" or whether she was the “author of her own misfortune.”

She said the court's sole task was to assess whether the decision to strip Begum of her citizenship was unlawful.

“Since it was not, Ms Begum’s appeal is dismissed,” the judge added.

Carr said any arguments over the consequences of the unanimous judgment, which could include a bid to appeal at Britain's Supreme Court, will be adjourned for seven days.

Begum's lawyer indicated that a further challenge was on the cards.

“I think the only thing we can really say for certainty is that we are going to keep fighting," Daniel Furner said outside the Royal Courts of Justice.

“I want to say that I’m sorry to Shamima and to her family that after five years of fighting she still hasn’t received justice in a British court and to promise her and promise the government that we are not going to stop fighting until she does get justice and until she is safely back home," he added.

Begum's legal team argued that the decision by Britain's then interior minister Sajid Javid, left her stateless and that she should have been treated as a child trafficking victim, not a security risk.

The British government claimed she could seek a Bangladeshi passport based on family ties. But Begum’s family argued that she was from the UK and never held a Bangladeshi passport.

Javid said he welcomed the ruling which “upheld” his decision.

“This is a complex case but home secretaries should have the power to prevent anyone entering our country who is assessed to pose a threat to it," he said.

A number of campaigners voiced their disappointment after the ruling.

“The power to banish a citizen like this simply shouldn’t exist in the modern world, not least when we’re talking about a person who was seriously exploited as a child," said Steve Valdez-Symonds, Amnesty International UK’s refugee and migrant rights director.