The US Treasury Secretary has announced that Washington intends to effectively halt Iranian airlines’ international operations from Wednesday, September 23, 2026, by pressuring aviation service providers. The move will be enforced by threatening foreign companies with secondary sanctions and cutting off their access to the US financial system.

Scott Bessent, the US Treasury Secretary, told CNBC on Monday that companies providing Iranian airlines with fuel, airport services or ticketing facilities could lose access to the US dollar-based financial system.

According to Bessent, Washington’s goal is to prevent Iranian airlines from obtaining the services they need at foreign airports to continue operating from September 23.

The remarks follow a sweeping package of US aviation sanctions announced by the Treasury Department on September 8. On that day, the US Office of Foreign Assets Control added 27 Iranian airlines not previously covered by the measures to its sanctions list. The Treasury Department said the move means all active Iranian airlines are now subject to US sanctions.

The US has also sanctioned several foreign companies and intermediaries involved in the sale, transport, servicing and supply of aircraft to Iranian airlines. It warned that any foreign company or individual providing services to sanctioned Iranian carriers could face secondary sanctions.

The deadline for the expiry of certain aviation exemptions is also September 23. Under a temporary licence issued by the US Treasury Department, some activities involving overflight, refuelling and emergency repairs, as well as certain aircraft-related transactions, may continue only until the early hours of September 23.

The restrictions have already had an impact ahead of the deadline. Mahan Air announced that its flights from Tehran to Muscat had been suspended from September 17, while services to Istanbul and Ankara would be suspended from September 21 until further notice. The airline said the decisions followed notifications from aviation authorities in Oman and Turkey.

However, Iranian aviation officials say the new sanctions do not yet amount to a complete halt to Iranian airlines’ international flights. Majid Akhavan, spokesperson for Iran’s Civil Aviation Organization, said on September 21 that the current restrictions mainly affected some Mahan Air routes, while other Iranian airlines continued to operate international services.

The measures taking effect on September 23 therefore do not constitute a “global order to shut down Iranian airlines.” Rather, they mark a new phase of US sanctions pressure aimed at denying the carriers access to fuel, airport services, ticket sales, financial services and other facilities required for international flights.