As Turkish warplanes bomb U.S.-backed Kurdish allies in northeastern Syria, the Trump Administration has yet to draw up a strategy to safeguard and maintain the more than 30 detention camps that hold tens of thousands of ISIS fighters, families and sympathizers spread across the region.

The Kurds, part of the U.S.-allied Syrian Democratic Forces, control facilities holding about 11,000 ISIS detainees across northern Syria. They also run a camp for internally displaced persons known as al-Hol, in northeastern Syria, that holds nearly 70,000 people. Among them are thousands of ISIS family members, according to a recent Defense Department Inspector General’s report.

The U.S. military has no plans to take over these camps and, with only about 1,000 total troops inside Syria, is not prepared to do so, U.S. officials told TIME. If the Kurds abandon their guard posts to defend their homes against the Turkish military incursion, thousands of ISIS operatives are likely to escape, U.S. military, diplomatic and intelligence officials have concluded.

Past and present U.S. military commanders have shared that assessment directly with President Donald Trump, but he has rebuffed the warnings and demanded that Turkey take control of the camps, the officials say. Most of the camps remain outside the area that Turkey is expected to occupy, and the Kurds have said they will remain in control over the detainees. But that may prove difficult if fighting in their home territory intensifies. In early 2018, hundreds of Kurds opted to abandon fighting positions against ISIS in eastern Syria to assist Kurdish forces fighting Turkish military in another skirmish in Afrin, in northwestern Syria.

Trump maintains that Turkey can, and will, take over control of the camps as part of their offensive. “Fighting between various groups that has been going on for hundreds of years. USA should never have been in Middle East,” he tweeted Wednesday. “Moved our 50 soldiers out. Turkey MUST take over captured ISIS fighters that Europe refused to have returned. The stupid endless wars, for us, are ending!”

A peaceful handover of the camps to the Turkish military is unlikely, U.S., European, and Middle East officials warn. The threat is complicated, U.S. intelligence officials say, by an unknown number of young refugees that have been radicalized by the abysmal conditions inside the camps and the proselytizing of ISIS members detained there. “If they are released, the task of identifying potential terrorists has been compounded by what’s been happening in the camps,” said one U.S. official, who was not authorized to speak publicly on the matter.

Even though ISIS militants have lost control of major cities in Iraq or Syria, the terror group’s leadership ranks have proven resilient despite the five years of war. And ISIS has been quick to adapt to new circumstances. No longer capable of seizing and holding territory, the surviving foot soldiers have instead gone back to its guerrilla roots by embedding constellations of sleeper cells in both countries to routinely carry out ambushes, bombings and assassinations. “The fact that (ISIS) is no longer a caliphate doesn’t mean it’s been defeated,” says the U.S. official. “Instead, it’s metastasizing.”

The U.S. has long known the detention facilities are a problem, but has failed to come up with a solution. For two years, the U.S. has pleaded with European and Arab allies to take custody of fighters held in the camps. It’s estimated that about 2,000 of the 11,000 ISIS prisoners are from more than 40 countries other than Syria and Iraq. With few exceptions, the nations refused to accept their countrymen and the United States was repeatedly rebuffed. “There does have to be a Plan B of what comes next,” Michael Mulroy, Deputy Assistant Secretary of Defense for the Middle East, said Oct. 2 at the Council on Foreign Relations. “I can’t declare what that is today because, quite frankly, we haven’t developed it entirely.”

The U.S. previously learned lessons the hard way after the 2003 invasion of Iraq and the notorious prison at Camp Bucca, which inadvertently came to serve as an incubator for Sunni jihadism. Many ISIS leaders, including Abu Bakr al-Baghdadi, initially met there while incarcerated. ISIS ranks were later swollen with fighters who escaped in a series of well-planned prison breaks. In April 2014, the militants helped topple the Syrian provincial capital of Raqqa, which it made its Syrian capital, and eight months later it took over parts of the Iraqi cities of Ramadi and Fallujah. The lightning offensive across Iraq and Syria ultimately resulted in the seizure of territory the size of Britain.

“We better pay close attention to what happens, or what failed to happen, regarding the thousands of detainees that up until now have been in Kurdish custody,” says Michael Nagata, who retired as Army Lieutenant General and strategy director from the National Counterterrorism Center in August. “It’s increasingly becoming hard for me to see the future of these detainees—many of which are no-kidding ISIS terrorists—ending in our favor. If a disaster happens as a result of this population being freed, there’s a big chunk of the world that’s going to blame the United States.”

—with reporting by Kimberly Dozier

Write to W.J. Hennigan at william.hennigan@time.com.