Financial authorities in the U.S. say they are reviewing the Russian government’s growing grip on Citgo Petroleum Corp. amid growing concerns that Moscow is looking to use energy supplies as a political weapon. State and Treasury Department officials are reported to be worried by the amassed debt the Kremlin has acquired via its state-owned oil giant Rosneft in the U.S. unit of Citgo, which is owned by Venezuela’s increasingly troubled state-run oil industry. Rosneft’s stake is near a controlling interest, and officials fear a debt default could put the Kremlin in a prime position to engineer a takeover. “This is an issue that I’m aware of,” Treasury Secretary Steven Mnuchin told a congressional hearing Thursday. “I can assure you that this, like any other national-security issue, will be reviewed.” Citgo has three oil refineries in the U.S., in addition to nine pipelines and almost 50 petroleum platforms.