A U.S.-led air campaign aimed at crippling the Islamic State’s oil business knocked out the militant’s main oil infrastructure in Syria, dealing a major blow to the group’s finances, U.S. officials said Tuesday.

The airstrikes have largely shut down the Deir ez-Zorfacility in Syria, which accounted for about two-thirds of the Islamic State’s oil revenue, said Col. Steve Warren, the U.S. military spokesman in Baghdad. “We do believe we pretty much turned off the Deir ez-Zor oil capacity,” he said.

The damage follows a month-long air campaign aimed at crippling the Islamic State’s black market oil business. […]