Dealing with state-owned Russian financial institutions—already a risky proposition for many U.S. companies—is even riskier now in the wake of the Treasury Department’s announcement Monday that it had sanctioned a Russian bank for allegedly attempting to sidestep U.S. sanctions on Venezuela, according to a former U.S. sanctions official.

The Treasury Department’s Office of Foreign Assets Control added Moscow-based Evrofinance Mosnarbank to the U.S. sanctions list after finding the bank had continued to “maintain its significant relationship” with the regime of Venezuelan President Nicolas Maduro.