The United States has transferred its first and only detainee from the fight against the Islamic State in Iraq and the Levant (ISIL) into Iraqi Kurdish custody, a seemingly ad hoc decision that raises new questions about whether President Barack Obama – who has vowed to close controversial Bush-era detention centers like Guantánamo Bay – has a plan for detaining "terror suspects" should they be rounded up in greater numbers as the anti-ISIL fight drags on.

The Pentagon had been opaque about its plans for Umm Sayyaf, the wife of an ISIL commander known as Abu Sayyaf who was captured in a May 15 raid in eastern Syria that also killed her husband. Sayyaf, an Iraqi citizen whose real name is Nasrin Asad Ibrahim, was apparently being held as a "law of war" detainee somewhere near the Iraqi Kurdish regional capital of Erbil and interrogated by a U.S. intelligence unit. Few other details were made public, spurring critics to argue that the U.S. needed to either bring charges against Sayyaf – who was suspected of playing a role in the kidnapping of American Kayla Mueller – or let her free.

In a statement Thursday night, however, the Pentagon said Sayyaf had been transferred to the Iraqi Kurdistan Regional Government’s Ministry of Interior, a decision it said was “consistent with [Department of Defense] policy to detain, interrogate, and, where appropriate, seek the prosecution of individuals who are captured on the battlefield.” It was not clear why she had been turned over to the semi-autonomous Kurdish government rather than the central government in Baghdad, but the statement seemed to suggest that she would ultimately face charges in Iraq.

Legal experts interpreted the decision to pass Sayyaf off to Iraq as something of a workaround for the Obama administration, which has promised to end CIA torture programs and empty out Bush’s “war on terror” detention facilities – including Guantanamo Bay, where suspects were often held indefinitely and without charge.

“Now that Gitmo is off the table, the question has been what do you do with any new detainees?” said Jens Ohlin, an expert on national security law at Cornell University Law School. “I think this was probably the best solution they could find right now.”

Obama has detained a relatively small number of “terror” suspects during his tenure, in part, critics say, to dodge these questions. Rights groups further accuse him of preferring to simply assassinate high-value targets through secretive drone strikes, rather than wrangle a legal justification for their detention. More than 2,400 people have been killed in U.S. drone strikes in Pakistan, Yemen and Somalia since Obama took office in 2009.

But handing Sayyaf over to Iraq poses legal and ethical problems of its own, given the Iraqi government’s well-documented history of torturing suspected “terrorists.” Under non-refoulement, a principle of international law, states may not transfer an individual within their control over to another state that is liable to violate their rights after the transfer, as Nathalie Weizmann and Rebecca Ingber explained in a recent post to national security blog, Lawfare. “It will therefore be critical to know the exact language of any transfer agreement to see what specific assurances the Iraqi government might provide,” they wrote, in advance of Sayyaf's transfer.

Separate sticky legal issues, national security experts said that simply transferring ISIL detainees to partners in the region will not prove a blanket solution if the fight against ISIL drags on. “If you’re talking about one detainee, you can try to find an ad hoc set-up like that,” explained Bobby Chesney, a law professor at the University of Texas who specializes in national security law. “But if we detained ISIL members as often as we shot them, you’d have to come up with some sort of plan.”

In Sayyaf’s case, it was not difficult to convince the Iraqi government to take back one of its own citizens. According to the Wall Street Journal, which first reported the transfer, it was quite eager to do so. If Sayyaf had been Syrian, however, turning her over to the regime of President Bashar al-Assad – which has systematically killed and tortured thousands of political prisoners since the war began in 2011 – would have been out of the question. In that event, “would Iraqis really have been up for taking her? You can always induce countries to do it here and there, but it’s not obvious how scalable this model is,” Chesney added.

The U.S. has so far limited its involvement in Syria to airstrikes, with only occasional raids like the one that brought Sayyaf into Delta Force custody. Obama has pledged not to send U.S. ground forces into combat in Syria or Iraq, where he only recently withdrew U.S. forces. But if ISIL continues to prove resilient, many fear the war will intensify and the U.S. may see an imperative to round up and interrogate ISIL members in larger numbers.

“That points to broader and recurring question: does the Obama administration have a viable detention policy for the future?” Ohlin said. “At some point that bridge is going to have to be crossed.”