Treasury Undersecretary David Cohen said Oct. 23 that the US government is in "the early stages" of a complex campaign to cut off funds to the group that calls itself the Islamic State (IS) — an effort complicated by collusion between IS and the regime of Syrian President Bashar al-Assad and the refusal of Qatar and Kuwait to act against several known terrorist financiers.

Cohen, in a rare public appearance in Washington, told an audience at the Carnegie Endowment for International Peace that the United States was also working with Iraqi authorities to try to prevent IS from using banks in captured territory without completely shutting down "all financial activity in those areas" and further penalizing their suffering residents.

IS is the “best-funded terrorist organization we have confronted,” Cohen said. He said the group earns at least $1-2 million a day from selling oil and at least $20 million a year in ransoms for kidnap victims. It also amasses money, he said, from selling women into sexual slavery, looting antiquities, stealing agricultural products and other forms of extortion inflicted on the millions of Iraqis and Syrians under its control.

"We have no silver bullet or secret weapon to empty ISIL's coffers overnight," Cohen said, using an alternative acronym for the group. But Cohen, who heads the Treasury department dealing with financial intelligence, said his staff was using tools developed over the past 10 years of working to disrupt al-Qaeda and enforce other sanctions in a sustained effort that would show progress over time.