Deep into a seven-hour congressional hearing on Sept. 21, JPMorgan Chase & Co. CEO Jamie Dimon was in the hot seat, with Representative Brad Sherman, a Democrat from California, pressing him on whether his bank would sever ties with Russian companies, including energy giant Gazprom PJSC.

Banks like Dimon’s, Sherman argued, were exploiting a sanctions loophole to keep doing business in Russia despite its invasion of Ukraine.

"We are following the instructions of the American government as they asked us to do it,” Dimon responded before Sherman cut him off, setting his sights on Citigroup Inc.’s Jane Fraser with a similar inquiry.