President Donald Trump said Wednesday that the U.S. has moved some of the Islamic State prisoners amid fears some could escape custody as Turkey invades northeast Syria.

Turkey is attacking the U.S.-backed Syrian Defense Forces, a Kurdish force that battled the Islamic State group alongside American troops and now is responsible for guarding thousands of detained militants.

But guarding those prisoners is now expected to be less of a priority for the Kurdish forces as they rush to defend their territory against the invading Turkish military.

Trump told reporters at the White House that some of the “most dangerous” had been moved, but he did not say how many or where they had been taken.

“We’re putting them in different locations where it’s secure,” he said.

In March, Kurdish and U.S. forces cleared the last members of the Islamic State group from what was left of their self-declared caliphate, which once sprawled across a large part of Iraq and Syria.

U.S. officials said operations against remaining members of the Islamic State group are on hold following the invasion Wednesday by Turkey, which sees the Kurds as a threat and is trying to create a buffer zone between the territory held by the SDF and the Syrian border.

Kurdish forces hold thousands of Islamic State fighters in detention centers, and U.S. officials said that some Kurds left the prisons to join the fight but did not flee in large numbers. Officials said a small number of high-profile Islamic State detainees are being relocated, but thousands of others remain in custody and there are no immediate concerns the Kurds will completely abandon the facilities.

The officials, who spoke on condition of anonymity to discuss internal deliberations, said U.S. forces are not out doing patrols looking for Islamic State group fighters because their Kurdish partners are more focused on the Turkish fight.

About 30 to 50 U.S. troops were moved out of the way from two outposts in the border region. There are a number of U.S. forces in other bases just outside the so-called safe zone as well as in Manbij and other locations around the country. They have not been moved but are mainly staying in place to avoid attacks.

There are about 2,500 Islamic State foreign fighters being detained in Syria, along with about 10,000 fighters from Syria and Iraq.

(AP)