"Despite losing its territorial 'caliphate,' the Islamic State in Iraq and Syria (ISIS) solidified its insurgent capabilities in Iraq and was re-surging in Syria," the report, which was published on Tuesday, warned.
President Donald Trump has repeatedly touted his administration's role in driving the terror group from areas under its territorial control, telling a Cabinet meeting last month, "We did a great job with the caliphate. We have 100% of the caliphate, and we're rapidly pulling out of Syria." But the new report said the partial withdrawal of some US troops from Syria has already impacted the fight against the remnants of ISIS, making it harder to advise local allies on the ground and depriving the US of the ability to monitor areas that are described as potential recruiting zones that would allow the group to replenish its ranks.
The report, from the lead inspector general for Operation Inherent Resolve, the official name for the US-led operation fighting ISIS, covers the period April 1 to June 30, 2019.
"The reduction of US forces has decreased the support available for Syrian partner forces at a time when their forces need more training and equipping to respond to the ISIS resurgence," Glenn Fine, the principal deputy inspector general, wrote in a message accompanying the report.
The report warns that because of the reduction in personnel, the US and its local allies were unable to closely monitor the al-Hol internally displaced persons camp, a situation that has allowed "ISIS ideology to spread 'uncontested' in the camp," potentially allowing ISIS to replenish its ranks among the tens of thousands of inhabitants.