The Obama administration is warning European countries and companies to shut out a sanctioned Iranian airline or risk US retaliation, Treasury officials told Al-Monitor.

US officials have long said that they retain the ability to sanction entities that do business with Mahan Air because of its alleged ties to the Islamic Revolutionary Guard Corps (IRGC). Those past remarks, however, have mostly focused on the sale of aircraft and parts as well as banking services, not on behind-the-scenes efforts to derail the airline's plans to further expand its flights to Europe and elsewhere around the globe.

"Treasury is engaging closely with stakeholders around the world, including our partners in Europe, regarding our sanctions targeting Iran," a Treasury official told Al-Monitor. "Regarding Mahan Air specifically, we are doing this by working with our partners to prevent Mahan Air from acquiring aircraft and aircraft parts and software, preventing the opening of new routes and working to get existing routes canceled."

The Treasury official made clear that despite the Iran deal, US sanctions officials "retain sanctions on Mahan Air for its support to terrorism and will continue to use this authority to target the airline." The deal, the official said, "does not preclude us from designating any entities that support Mahan Air or facilitate its activities."