ISIS is making a comeback in Syria at a time when the United States is largely drawing down its troop presence in the country, according to a Pentagon report.

“Although it has lost its territory, ISIS has strengthened its rebellious capabilities in Iraq and resumed operations in Syria,” the document reads. The Pentagon has concluded that ISIS has been able to regroup and support operations in both countries, partly because local forces are still unable to sustain long-term operations or effectively hold the territory they fought to liberate from ISIS since 2014.

ISIS’ reconstitution has coincided with a decision by the White House to partially withdraw the American operational forces that have been in Syria since the terrorist organisation first appeared over five years ago.

President Donald J. Trump abruptly announced the withdrawal of the majority of the 2,000 American soldiers deployed in northeastern Syria and declared that ISIS had been completely destroyed. Trump’s sudden proclamation, which had reportedly not been endorsed by his military or security advisors but was largely supported by those in his ideological inner circle, prompted Trump’s widely respected Secretary of Defense, Jim Mattis, to resign in protest.

Washington’s decision to pull most of its military advisor from Syria was heavily criticised by the American-backed Syrian Democratic Forces and the Kurdish YPG – the US’ two key allies in the eight-year, multi-sided conflict.