Wilbur Ross has an interest in Navigator Holdings – which earns millions a year transporting oil and gas for Russian energy firm Sibur.
When he joined Mr Trump’s cabinet Mr Ross divested his interests in 80 companies.
But kept stakes in a number of companies – including a number in the Cayman Islands that link him to Navigator.
One shareholder of Sibur is President Putin’s son in law – Kirill Shamalov.
Two other major Sibur shareholders are under some form of US sanctions.