WASHINGTON—Iran established a clandestine banking and finance system to handle tens of billions of dollars in annual trade banned under U.S.-led sanctions, enabling Tehran to endure the economic siege and giving it leverage in multilateral nuclear talks, according to Western diplomats, intelligence officials and documents.
The system, which comprises accounts in foreign commercial banks, proxy companies registered outside the country, firms that coordinate the banned trade, and a transaction clearinghouse within Iran, has helped Tehran resist the Biden administration’s pressure to rejoin the 2015 nuclear deal, buying it time to advance its nuclear program even while negotiations were under way. Officials say they are closing in on a deal, with the release of two British women in recent days foreshadowing a potential agreement within days.