British Home Secretary Sajid Javid said late Wednesday that he would not render any individual “stateless.” But Shamima Begum, a 19-year-old Briton, and other foreign nationals who moved to the Islamic State’s self-proclaimed caliphate and now want to return home may ultimately be left in citizenship limbo.

Javid made the statement after the British government announced that Begum, who was 15 when she left for Syria to marry a fighter with the extremist group, also known as ISIS, would be stripped of her British citizenship but could claim Bangladeshi citizenship because of her family’s Bangladeshi heritage. Bangladesh announced, however, that it would not give Begum citizenship.

“I’m not going to talk about an individual, but I can be clear on the point that I would not take a decision, and I believe none of my predecessors ever have taken a decision, that at the point the decision is taken would leave that individual stateless,” Javid said.

Javid did not specify whether that meant Britain would still go ahead with its decision to strip Begum of her citizenship. “My number one job is to do whatever I can to keep this country safe,” he said.

Begum’s case has garnered international attention, highlighting the legal limbo faced by foreign fighters and their family members as they try to return home to face justice. With the Islamic State on the verge of collapse in Syria, Britain and other countries are almost certainly going to be confronted with more such cases.

“People are likely to be left in limbo in war zones unable to seek safety or basic human rights,” said Devyani Prabhat, who researches and teaches migration, citizenship and nationality at the University of Bristol Law School.

The problem will not be limited to Britain or Europe. In the United States, on the same day that Javid made his statement, President Trump said he had instructed Secretary of State Mike Pompeo not to allow Hoda Muthana, a woman from Alabama who left to join the Islamic State in 2014, back into the country.

Pompeo issued a statement saying Muthana is not a U.S. citizen. Her father was a Yemeni diplomat, and children born to foreign diplomats in the United States are not granted birthright U.S. citizenship. But a family representative said Muthana’s father had stepped down from his diplomatic role before she was born and that she was indeed born a U.S. citizen and had a valid U.S. passport.

Under international law, it is illegal to strip someone of citizenship if doing so would leave that person stateless. But that does not mean governments cannot try to use loopholes to do just that.

“Measures depriving citizens of nationality on national security grounds are being used with increasing frequency across Europe,” Michelle Foster, director of the Peter McMullin Center on Statelessness in Melbourne, said in an email to WorldViews. “Indeed, the so-called foreign fighter phenomenon has led to [an] attempt to introduce and widen powers of citizenship deprivation beyond Europe, as well, including in Australia. Moreover, states are engaged in a cross-jurisdictional exchange, with many countries importing increasingly restrictive and discretionary policies from other jurisdictions.”

Foster noted that, in 2014, Britain added a “temporal predictive dimension to its dual citizenship determination, such that the secretary of state need only have reasonable grounds for believing that a person is able to become a national of another country.” In other words, the government can argue that the person it is trying to strip of citizenship is going to get citizenship elsewhere — giving the government grounds to revoke the person’s existing legal status.

In Begum’s case, Prabhat said in an email: “I think the U.K. authorities will try to rely on Bangladeshi nationality legislation, which states that a person of Bangladeshi heritage has automatic Bangladeshi citizenship (through bloodlinks). However, whether or not this is actual practice or indeed the actual position in Bangladeshi law (including case law), Shamima is now at real risk of actual statelessness, as they will not accept her or take responsibility for her.”

There is also the reality that having citizenship and being able to return home are, or can be, two very different things.

“If you were sitting in a refugee camp of Syria, regardless of whatever passport you hold, you are effectively stateless, and you’re not getting any protection,” said Brad Blitz, a professor at Middlesex University London who works on migration, statelessness and citizenship. “Everyone else in that refugee camp is also effectively stateless.”

Javid, Blitz said, may be forced to acknowledge that he cannot strip Begum of her British citizenship. “But even if they do so,” he said, “no one will be sending a rescue plane to take her out of there.”

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