Kurdish forces are now holding them captive, and they both want to go home. On Tuesday, the U.K. informed Begum that it had revoked her citizenship. The next day, Secretary of State Mike Pompeo said that Muthana, too, is someone else’s problem. He declared that she was never a citizen to begin with because she was born in the United States while her father was here as a Yemeni diplomat, and children born to diplomats cannot claim birthright American citizenship. (Muthana’s family claims that the father had left diplomatic service when she was born, and that they gave the Obama administration proof of that when first confronted with this argument in 2016.) The upshot for both women, now marooned in the Syrian desert, is that they are alone and have very grim futures.

How easy should it be to give up your citizenship? In the era of Oswald, it could be difficult—like joining an especially selective monastic order that turns away aspirants until they kneel in the snow for a few days outside the monastery or consulate’s doors. Now a U.S. citizen can stop being American with a single visit to a consulate. (Most renounce not for ideological reasons but to avoid the complications of living as an American expatriate, subject to dual taxation and bureaucratic requirements far more onerous than for expatriates of almost any other country.)

But to argue that these women have given up their citizenship through informal means—by tweeting ghoulishly, burning a passport, or joining a terrorist group—is still a novelty and, according to an emerging consensus, a bad idea. Most terrorism experts seem to agree that stripping the citizenship of ISIS fighters is either imprudent or illegal or both.

Under American law, the rule of denaturalization is by now relatively clear: No one can be denaturalized except with the determination of a federal court. It was not always so. Patrick Weil, a legal historian at the French National Center for Scientific Research, says that the involuntary stripping of citizenship happened “on a massive scale” in the United States in the early half of the 20th century, with some 140,000 Americans losing their citizenship for offenses much milder than incitement to mass murder. Only after Supreme Court decisions in the late 1960s did the process of forced denaturalization become so difficult that it rarely occurs. If Muthana was indeed born American, I expect the courts will agree that American she remains.

(In the U.K., since 2002 the reverse has been true: The government may deprive people of citizenship through executive power alone. Britain has taken away citizenship from at least 373 people since 2006.)

Those who wish to de-Americanize Muthana and people like her invoke security and morality. Is it safe to take American terrorists back and deal with them through our justice system—perhaps letting them proselytize in our prisons and recruit more jihadists? Muthana is practically begging to be put on trial and found guilty, as long as she never has to leave America again. But of the dozens of other Americans who traveled to the Islamic State, and the thousands of non-Americans, one can reasonably expect that a few will remain permanent threats. A robust finding of the ISIS era is that a few charismatic terrorist recruiters have outsized effects, sometimes luring hundreds of others. Having them in easy contact with potential American recruits is a metastatic problem. Of course, having them wandering the Earth, far away from American oversight, carries risks of its own. Saudi Arabia revoked the citizenship of Osama bin Laden in 1994, and had less control over him thereafter.