American forces are still needed there, particularly to ensure the security of detention camps holding tens of thousands of former IS fighters and family members, Austin claimed Wednesday in one of his final interviews before he leaves office.

According to estimates, there are as many as 8,000-10,000 IS fighters in the camps, and at least 2,000 of them are considered to be very dangerous.

If Syria is left unprotected, “I think ISIS fighters would enter back into the mainstream,” Austin said at Ramstein Air Base in Germany, where he traveled to discuss military aid for Ukraine with about 50 partner nations. He was using another acronym for the Islamic State group.

“I think that we still have some work to do in terms of keeping a foot on the throat of ISIS," he said.

President-elect Donald Trump tried to withdraw all forces from Syria in 2018 during his first term, which prompted the resignation of former Defense Secretary Jim Mattis. As the Hayat Tahrir al-Sham group, or HTS, advanced against Assad last month, Trump posted on social media that the U.S. military needed to stay out of the conflict.

In a surprise announcement, the Defense Department disclosed in December that the U.S. have more than doubled the number of American troops in Syria to support the fight ISIS, an increase that predates the fall of Bashar al-Assad’s regime. 

The U.S. has now about 2,000 troops in Syria to counter IS, up significantly from the 900 forces that officials said for years was the total number there.

The continued presence of U.S. troops was put into question after a lightning insurgency ousted Assad on Dec. 8, ending his family’s decadeslong rule.

U.S. forces have worked with the Kurdish-led Syrian Democratic Forces on operations against IS, providing cover for the group that Turkey considers an affiliate of the Kurdistan Workers’ Party, or PKK, which it identifies as a terror organization.

The SDF “have been good partners. At some point, the SDF may very well be absorbed into the Syrian military and then Syria would own all the (IS detention) camps and hopefully keep control of them,” Austin said. "But for now I think we have to protect our interests there.”

In 2019, then-US President Trump directly addressed those interests, saying during a White House news conference next to Turkish President Recep Tayyip Erdogan that the US had “left troops behind only for the oil.”

The US military has occupied Syrian sovereign territory since 2014, preventing Damascus from accessing its own oil and wheat fields.

* This story was edited by Ahram Online.