For years, Artem Uss had appeared in Russian media as the owner of fancy real estate, luxury cars and Italian hotels. Now U.S. officials allege he’s at the center of a suspected secret supply chain that prosecutors say used American technology to support Russian President Vladimir Putin’s war in Ukraine.

The son of a Siberian governor was arrested last year on charges that he and his associates defrauded the U.S. and its companies and also violated sanctions by selling sensitive technologies from the U.S. to Russia via intermediaries in nonsanctioned countries. He’s the most politically connected Russian to be indicted by the U.S. as Washington races to choke off Moscow’s access to chips used in weapons systems. Uss has denied any wrongdoing and is now in the midst of an extradition battle in Milan.

Court documents from the Uss case and others like it show how Russia allegedly built a secret pipeline for years before the war to ensure the supply of semiconductors to the country despite U.S. controls. Those well-honed tactics are now helping Russian operators rebuild dismantled networks and deceive publicly listed U.S. tech companies, according to customs data, indictments and people familiar with the matter, who weren’t authorized to speak to the media.