ISIS have suffered serious reverses recently losing their capital Raqqa in late 2017. The group has continued fighting using insurgent tactics. In December President Trump claimed ISIS had been defeated in Syria.
He commented: “We have defeated ISIS in Syria, my only reason for being there during the Trump Presidency.”
Trump announced the withdrawal of US ground forces from Syria, though aerial bombing will continue.
The leaked document is a draft of a quarterly Pentagon report on the campaign against ISIS, which is due to be released next week.
It warns the group could retake ungoverned parts of Syria within a matter of months, and is determined to recreate its physical caliphate.
ISIS shot to prominence in 2014 with a series of advances which saw them capture Mosul, Iraq’s third city, and reach the outskirts of Baghdad.
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After taking Mosul they executed thousands of Iraqi security personnel, and forced women from the Yazidi religious minority into sexual slavery.
The group was gradually pushed back by Iraqi and Kurdish forces, backed by western special forces and air power.
The US is currently in the process of withdrawing land forces from Syria, who should be out by mid-Spring.
However speaking to Fox News Secretary of State Mike Pompeo warned the group still poses a risk.
He said: “We need to continue to do all that we can to make sure that there’s not a resurgence of ISIS or that all the other variants of that terror regime continue to be under pressure.”
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On Tuesday, during a Senate Intelligence Committee hearing, Director of National Intelligence Dan Coats said ISIS “still commands thousands of fighters in Iraq and Syria”.
He added the group had reverted to its “guerrilla warfare roots”.
ISIS continues to have affiliates active around the world.
It claimed responsibility for a Philippines Cathedral bombing which killed twenty people on January 27.