Defense Secretary Mark Esper has confirmed that a nightmare scenario has come to pass: Captured ISIS fighters are escaping as a result of Turkey's invasion of Kurdish-held northeast Syria.

Turkey's incursion has led to “the release of many dangerous ISIS detainees,” Esper said in a statement on Monday.

While Esper did not say how many prisoners who had been held by the Syrian Democratic Forces had managed to escape, nearly 800 women and children who are related to ISIS fighters were able to flee a Kurdish prison camp at Ain Issa after it was attacked by the Turks, according to Reuters.

Even worse: Turkey's Islamic proxies are freeing ISIS fighters from unguarded prisons, Foreign Policy reporter Lara Seligman brought to light on Monday.

Kurdish fighters captured tens of thousands of ISIS fighters and their families as the caliphate crumbled. Defense officials had persistently warned that the Syrian Democratic Forces were not prepared to hold that many prisoners indefinitely, and ISIS leader Abu Bakr al-Baghdadi has urged his followers to launch massive jail breaks to replenish the terrorist group's ranks.

President Donald Trump tweeted on Monday that he suspected it was the Kurds who were intentionally freeing ISIS fighters as part of a ploy to win U.S. support again.

“Kurds may be releasing some to get us involved,” the president tweeted, without providing any evidence. “Easily recaptured by Turkey or European Nations from where many came, but they should move quickly.”

During an interagency conference call on Monday, a senior administration official was unable to say how many ISIS prisoners have escaped and whether any of those detainees freed include ISIS fighters.

“We don't have a large footprint in Syria,” the official said on condition of anonymity. “We can't be everywhere and know everything. From DoD's perspective, we're continuing to monitor and try to corroborate as much information as we are seeing in open source information or from other on the ground. I cannot corroborate at this point exactly who may have broken out of the prisons at this point.”

Some U.S. service members will remain to the Al Tanf garrison, said the official, who would not provide a timeline for when the rest of the U.S. troops in Syria will leave the country.

UPDATE: This story was updated on Oct. 14 with comments from a senior administration official.