Islamic State terrorists have a secret war chest of up to $300 million in cash to help sustain future operations and fund new attacks on the West, according to a United Nations report.

The money is “bulk-stored” in its last remaining stronghold area, while the rest has been smuggled abroad or invested in legitimate businesses.

Even if Islamic State militants are forced out of their last Syria holdout this week, the group has other financial assets “with a strategic view to funding larger-scale attacks once the opportunity arises again,” the report says.

The news that Islamic State has the financial means to continue its fight even as its “caliphate” shrinks to nothing comes as U.S.-backed and Kurdish-led Syrian forces begin a final push to defeat the terror group in the last tiny pocket the extremists hold in eastern Syria.

As Breitbart News reports, Syrian Democratic Forces spokesman Mustafa Bali tweeted that the offensive began last Saturday after more than 20,000 civilians were evacuated from the IS-held area in the eastern province of Deir el-Zour. An SDF statement said the offensive was focused on the village of Baghouz.

The SDF, backed by U.S. air power, has driven IS from large swaths of territory it once controlled in northern and eastern Syria, confining the extremists to a small pocket of land near the border with Iraq.

Tens of thousands of people, mostly women and children related to terror fighters, have fled that onslught to opposition territory, many of them claiming they were not supporters of the terror group.

But the U.N report also warns that foreign fighters and the extremists’ dependents will still pose a threat even after the Islamic State organization is defeated.

“Foreign terrorist fighters leaving the conflict zone, or prior returnees becoming active again on release from prison or for other reasons, will increase the threat,” the report says.

“The handling of dependants is particularly challenging. Radicalized women and traumatized minors may also pose a serious threat,” it continues.

And the report notes that despite losing physical ground, Islamic State still has up to 18,000 loyal members in its ranks in Syria and Iraq – including 3,000 foreign terrorist fighters.

The report also confirmed that the group is still led by Abu Bakr al-Baghdadi – who has not been seen in public since 2014, and has been pronounced dead on several occasions.