Former Defense Secretary James Mattis said the Islamic State has not been defeated and could “resurge” if military pressure eases on the terror group because of the fighting in Syria between Turkish and Kurdish forces.

“I think Secretary of State Pompeo, the intelligence services, the foreign countries that are working with us have it about right that ISIS is not defeated. We have got to keep the pressure on ISIS so they don’t recover,” Mattis told NBC News’ “Meet the Press” in an interview that will air Sunday.

His comments come as the US moved special operations troops from the Syria border after President Trump in a phone call last Sunday gave Turkey’s leader Recep Tayyip Erdogan the green light to move against the Kurds, who had fought alongside American troops against ISIS.

“You can pull your troops out, as President Obama learned the hard way, out of Iraq but the ‘enemy gets the vote’ as we say in the military. And in this case, if we don’t keep the pressure on then ISIS will resurge. It’s, it’s absolutely a given that they will come back,” said Mattis, a retired Marine Corps general.

Trump has defended his decision to give free rein to Turkish forces by saying the ISIS caliphate has been defeated and he wants to stop the US from fighting “endless wars” and bring troops back home.

But he has been met with bipartisan criticism, including from GOP Sen. Lindsey Graham, who has been a vocal backer of the president on other issues, and Senate Majority Leader Mitch McConnell.

Graham, of South Carolina, urged Trump to reverse course on Syria. “Every concern I had about President Trump’s Syria decision is coming true in spades. The reemergence of ISIS is on the way. And if you think only Europe is threatened – you are sadly mistaken,” Graham, the chairman of the Senate Judiciary Committee, wrote on Twitter Friday.

The assault on the Kurds, who lost 11,000 fighters in the battle against ISIS, has reduced their ability to keep watch on thousands of the terrorists they’re holding in makeshift prisons across Syria.

On Sunday, clashes between Kurdish and Turkish troops allowed hundreds of ISIS militants escape from a camp for displaced people about 20 miles away from the border, the Associated Press reported, citing Syrian Kurdish officials.

Around 950 ISIS supporters escaped after attacking guards and storming the gates of the camp in Ain Eissa.A US official told the wire service that the situation in northeastern Syria was “deteriorating rapidly” and US forces were losing communication with the Kurdish fighters.

The official also said US troops on the ground were in jeopardy of being “isolated” and could end up clashing with Turkey-backed Syrian forces.

Ankara considers the Kurds, members of the Syrian Democratic Forces, a terror group aligned with an insurgent group in side Turkey.

The Syrian Observatory for Human Rights, a monitoring group based in Britain, said Turkish warplanes struck targets near the base on Sunday, and camp residents fled when fighting broke out between Turkey-backed Syrian troops and Kurdish forces.