Russ Dallen, a partner in Caracas Capital Markets, a Florida-based company that monitors Venezuela’s energy sector, said information collected by the firm indicated the flights were carrying chemicals and equipment to help Venezuela restart its moribund domestic gas refineries. Maduro’s government, he said, appears to have paid for those parts — as well as the Iranian gasoline now in transit — with gold from the Central Bank.

“We track Central Bank reserves every month,” Dallen said. “They suddenly went down from April to May by $700 million.”