But in the years they were getting started, a key component of ISIS’s support came from wealthy individuals in the Arab Gulf States of Kuwait, Qatar and Saudi Arabia. Sometimes the support came with the tacit nod of approval from those regimes; often, it took advantage of poor money laundering protections in those states, according to officials, experts, and leaders of the Syrian opposition, which is fighting ISIS as well as the regime.

“Everybody knows the money is going through Kuwait and that it’s coming from the Arab Gulf,” said Andrew Tabler, senior fellow at the Washington Institute for Near East Studies. “Kuwait’s banking system and its money changers have long been a huge problem because they are a major conduit for money to extremist groups in Syria and now Iraq.”

Iraqi Prime Minister has been publicly accusing Saudi Arabia and Qatar of funding ISIS for months. Several reports have detailed how private Gulf funding to various Syrian rebel groups has splintered the Syrian opposition and paved the way for the rise of groups like ISIS and others.