( CNN) When a 19 -year-old British teenager who ran away to join ISIS in Syria announced her desire to return home, it blew open the long-simmering question of what governments should do with returning jihadis and their families.

In an interview with the BBC on Monday, she said the 2017 Manchester Arena bombing, in which 23 people died, was justified because of Western airstrikes in ISIS territory.

The public backlash was swift and by Tuesday, Britain announced its intention to strip Begum of her citizenship. Her family's lawyer Mohammed Akunjee said they wereconsidering “all legal boulevards to challenge the decision.”