A forthcoming Pentagon assessment is expected to warn that ISIS could regain lost territory in Syria within months without continued U.S. pressure, according to multiple reports.

NBC News reported Thursday that a draft of the Defense Department Inspector General's Quarterly Report about Operation Inherent Resolve warns that ISIS could regain territory within six to 12 months.

One U.S. official told CNN that some military and intelligence officials have concerns that ISIS could regain territory even sooner.

The Pentagon report is expected to be released next week. The Defense Department Inspector General's office told The Hill it does not comment on drafts.

The reported warning comes as the Pentagon continues to follow President Trump Donald John TrumpBubba Wallace to be driver of Michael Jordan, Denny Hamlin NASCAR team Graham: GOP will confirm Trump's Supreme Court nominee before the election Southwest Airlines, unions call for six-month extension of government aid MORE's December order to withdraw from Syria.

ADVERTISEMENT

Trump claimed at the time that ISIS was defeated in the country, saying it meant there was no reason to stay.

"We have defeated ISIS in Syria, my only reason for being there during the Trump Presidency," he tweeted Dec. 19.

However, multiple officials have contradicted the characterization of the situation in Syria and a U.S. intelligence report released Tuesday warned that lifting pressure on Syria could be dangerous.

“The group will exploit any reduction in [counterterrorism] pressure to strengthen its clandestine presence and accelerate rebuilding key capabilities, such as media production and external operations,” the report stated.

Trump rejected findings from Director of National Intelligence Dan Coats Daniel (Dan) Ray CoatsFBI chief says Russia is trying to interfere in election to undermine Biden The Hill's Morning Report - Sponsored by The Air Line Pilots Association - Trump, Biden renew push for Latino support Former Intel chief had 'deep suspicions' that Putin 'had something on Trump': book MORE and CIA Director Gina Haspel in a string of tweets on Wednesday, writing “perhaps Intelligence should go back to school!"

On Thursday, the Senate also offered a bipartisan rebuke of the president's Syria policy, marking the first time in the new Congress that the GOP caucus has formally broken with Trump.

Senators voted 68-23 to end debate on an amendment that warned Trump against drawing down troops in Syria and Afghanistan. Senators still need to hold a second vote to include the amendment on a foreign policy bill.