We don't have information on processing Russian invoices. You may want to ask this question on the AP & A2P Forums to see if any of our members can help. Some of them do business internationally and may have the expertise you seek.
I assume you have researched your vendors with the U.S. Department of Treasury Office of Foreign Asset Control (OFAC). If you click on the "Resources" tab of this webpage, you'll be able to search on their names to ensure it is legal to do business with them: https://www.treasury.gov/about/organizational-structure/offices/Pages/Office-of-Foreign-Assets-Control.aspx.