Since last month, U.S. warplanes have struck Islamic State's oil infrastructure in Syria in a stepped-up campaign of economic warfare that the United States estimates has cut the group's black-market earnings from oil by about a third.
In finding their targets, U.S. military planners have relied in part on an unconventional source of intelligence: access to banking records that provide insight into which refineries and oil pumps are generating cash for the extremist group, current and former officials say.
The intent is to choke off the Islamic State's funding by tracking its remaining ties to the global financial system. By identifying money flowing to and from the group, U.S. officials have been able to get a glimpse into how its black-market economy operates, people with knowledge of the effort have said.
That in turn has influenced decisions about targeting for air strikes in an effort that began before Islamic State's Nov. 13 attacks on Paris and has intensified since, they said. While Islamic State's access to formal banking has been restricted, it retains some ties that U.S. military and financial officials can use against it, the current and former officials said.
"We have done a really good job of largely keeping the Islamic State out of the formal financial system," said Matthew Levitt, who served as deputy assistant secretary for intelligence at the U.S. Treasury in the George W. Bush administration. "But we haven't been entirely successful, and that may not be a bad thing."
Economic warfare taken to a literal stage, then. We'll see if that slows down ISIS at all, but as long as the countries buying oil from the group are still acting like it's not a big deal, they'll just find other ways to fund terror.
They always do. There's only so much economic warfare you can wage before there's no economy left.