Syrian Democratic Forces fighters ride a pickup truck with Islamic State soldiers held as prisoners.Rodi Said / Reuters

Updated at 3:19 p.m. ET.

The prisoners were an emergency waiting to happen. For months, thousands of suspected Islamic State fighters from some 50 countries languished in makeshift jails in northeastern Syria; sometimes, a few broke out. But U.S.-backed Kurdish forces were, for the most part, keeping them locked up.

Then President Donald Trump ordered U.S. forces to withdraw from outposts in the area, clearing the way for the Turkish assault on America’s Kurdish partners in the fight on ISIS, and destroying the tenuous balance that has helped keep the Islamic State contained. Vice President Mike Pence’s announcement of a five-day pause in the fighting today—meant to give Kurdish forces time to leave territory within 20 miles of the Turkish border—also included the promise that Turkey would cooperate with the U.S. to guard prisoners. But it left unresolved the question of how those prisoners would be transferred from the custody of the Kurdish-led Syrian Democratic Forces.

Meanwhile, in the chaos of the days leading up to Tuesday’s withdrawal announcement from Trump, and with many Kurdish forces suddenly consumed with defending themselves, more suspected fighters reportedly broke out. Trump ventured yesterday that the number was probably fewer than 100, though as Defense One’s Katie Bo Williams reported, no one really knew. U.S. forces in the region were busy relocating to avoid the fighting. A Defense Department spokesman told me Kurdish forces were still manning the prisons, for now. But the U.S. has no plan to keep all those ISIS fighters off the battlefield if the Kurds leave the prisons. And just like that, what was once a festering but contained problem threatened to become a disaster, and no one could even say how bad.

For his part, Trump seems unconcerned with the details, speculating yesterday that the Turks or the Syrians could look after the prisoners, and saying that the prisoners who escaped were “the least dangerous”—before his own defense secretary, Mark Esper, said he didn’t know that to be true, according to Democratic Senator Chuck Schumer’s account of a chaotic meeting at the White House yesterday afternoon. That gathering yielded more insults than answers, with Trump calling House Speaker Nancy Pelosi a “third-grade” or “third-rate” politician (accounts vary) and having what she called a “very serious meltdown.” “President Trump: Tell us your plan to protect the US & reverse course in Syria. NOW,” Schumer tweeted afterward.

There was no plan. There was only a letter. Trump, who had told Turkish President Recep Tayyip Erdoğan in an October 6 phone call that U.S. troops would move out of the way of a planned Turkish assault, followed up days later with a slapdash missive in which he warned Erdoğan, “Don’t be a tough guy. Don’t be a fool!” and then concluded: “I will call you later.”

It was too late. By the time Trump’s phone call set a crisis in motion, U.S. diplomats were still, mostly unsuccessfully, trying to persuade countries to take their detainees in Syria back for trial and imprisonment at home. “It’s just a kick in the gut to the people who were trying to bring back these [ISIS prisoners],” said a U.S. official. Erdoğan, according to the BBC, threw Trump’s letter away. The Turkish assault went ahead on October 9. Reports of prison breaks soon followed.

Esper declared in a statement that Turkey’s “unacceptable incursion” had resulted “in the release of many dangerous ISIS detainees” and undermined the entire mission to defeat ISIS. A senior administration official told reporters on a background phone call this week: “Look, we don’t have a large footprint in Syria, so we can’t be everywhere and know everything. We are very concerned about the potential for detainee releases from the prisons and as well as the IDP [internally displaced persons] camps” holding families of ISIS suspects. Some 800 people had reportedly already escaped from a camp for ISIS family members by then, Kurdish sources told media outlets, though U.S. officials have not confirmed this. But the senior administration official’s comment also underscored the fact that, as U.S. forces retreat farther from northern Syria, they lose the ability to even know what’s happening in the camps and prisons there, let alone control it.

Even if none of this had happened—not the Trump-Erdoğan phone call, not the Turkish incursion, not the latest reported prisons breaks—the detainee issue would be a crisis. Since the defeat of the Islamic State’s territorial caliphate, the U.S. has relied on Kurdish-led militias to hold some 11,000 ISIS fighters, about 2,000 of whom were “foreign fighters” from outside Iraq and Syria, according to a Defense Department estimate. But officials have acknowledged that this was never a long-term solution; the Kurds were a non-state force running ad hoc detention centers in the desert, even as most prisoners’ home countries kept refusing to take back their citizens to stand trial.

So what’s the alternative? As of earlier this month, there wasn’t one. “There does have to be a Plan B of what we do next,” said Michael Mulroy, a deputy assistant secretary of defense for the Middle East, at a Washington event on Syria days before Trump’s call with Erdoğan. “I can’t declare what that is here today, because quite frankly, we haven’t developed it entirely.”

Still, U.S. officials recognized that other militant groups in the region, after seeming defeats, had mutated and regrouped before—and prison breaks had played a large part.

“We should remember that at the beginning of ISIS, they got a lot of their fighting, a lot of their combat power, by breaking people out of prison in places like Mosul,” Joseph Votel, the former commander of U.S. forces in the Middle East, said at an event in Washington last week. “Hundreds, thousands of fighters instantly joined like that.”

The ISIS leader Abu Bakr al-Baghdadi did time in a U.S.-run prison camp in Iraq. “It was within the confines of these overcrowded camps that the next iteration of terror germinated among detainees,” a brief from the Soufan Group, a private intelligence firm, noted in April. What would become the Islamic State’s leadership recognized the potential of these prisoners, and organized a campaign to free them.

The dynamic could well repeat itself in the cauldron of northern Syria today. The United States has taken custody of two of the most famous ISIS prisoners—the British-born men Alexanda Kotey and El Shafee Elsheikh, who are accused of being part of a cell that imprisoned, tortured, and beheaded Americans. The New York Times has reported, citing American officials, that the Kurds refused to transfer other prisoners to U.S. custody. On Sunday, Esper announced that the Turkish offensive was broader than the U.S. originally anticipated, and that 1,000 U.S. troops would be pulling out of northern Syria altogether, leaving them with even less insight into the network of Kurdish-run prisons in the area.

The Kurdish People’s Protection Units (YPG) have reportedly reduced but not abandoned their presence at the prisons. “The threat is more that the expanding war between Turkey and the YPG will engulf northern Syria and indirectly result in security gaps that allow ISIS to escape, either opportunistically or through coordinated attacks against limited security forces at the detention facilities,” Jennifer Cafarella, the research director at the Institute for the Study of War who has tracked the Syria conflict, wrote in an email.

The risks have spiked, but the policy is the same: Countries just need to take their citizens back. Most were unwilling before, and now they may be unable. As security deteriorates in northern Syria, there’s no obvious way to get prisoners out and back home even if their governments wanted them. Trump has suggested that Turkey can take over, but Turkey has shown little inclination so far. Trump officials meanwhile reiterate that sending the fighters home is the best solution. “We have tried very hard, over a period of months, to get the home countries for these detainees to take responsibility for them,” said a senior official on the phone call with reporters this week. “We think that is the logical resolution for this situation.”

The president has in the past threatened to have ISIS prisoners released, to menace European countries who won’t take back their citizens. Of the fighting between Turkey and the Kurdish forces U.S. officials keep insisting aren’t being abandoned, Trump asked of reporters yesterday: “What does that have to do with the United States of America, if they’re fighting over Syria’s land?”

And anyway, he said, the Kurds themselves are “no angels”—the Turkish branch of the group that until Sunday was America’s best ally in the fight against ISIS was, in the president’s words, “probably worse at terror and more of a terrorist threat, in many ways, than ISIS.”

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