Possibly the most worrying aspect of ISIS’s operational potential comes from its unprecedented wealth. According to files seized by Iraqi intelligence before the attack on Mosul, ISIS had £515 million in cash and assets. While it appears the seizure of funds from Mosul may have been initially overstated, it still would have resulted in tens of millions of pounds being taken.
ISIS has achieved this wealth mostly via captured oil facilities in Syria, the sale of rare antiquities seized in the conflict and in levying taxes on individuals and businesses in the regions it controls. In addition to this, it has also been funded by individuals in Kuwait, who appear to be supporting a variety of jihadist groups operating in Syria currently.