
Last month, U.S. fighter jets unleashed airstrikes against oil fields, refineries, and hundreds of tanker trucks near the Syrian city of Deir Ezzor. Dubbed Operation Tidal Wave II, the attacks were the latest phase in a campaign to bomb the Islamic State into bankruptcy, striking at the heart of the black-market economy and extortionist tax system that have underwritten the salaries of tens of thousands of extremist fighters.