Iraq has ordered its civil aviation authority to suspend Iranian flights to Baghdad airport from Wednesday, Reuters reported citing sources. This comes after US threatened secondary sanctions against airports and service providers that continue to handle Iranian carriers.The suspension will begin at midnight on Wednesday, the sources said. The Iraqi government is also discussing diverting Iranian Airways flights from Baghdad to Najaf airport, they added.The move comes after US Treasury Secretary Scott Bessent said on Monday that all Iranian airlines would be shut down from September 23 through the threat of secondary sanctions against aviation service providers, seven months into the war between the United States and Iran.Bessent told CNBC that airports and other companies servicing Iranian airlines could face severe consequences.“When Iranian airlines land at an airport, you cannot provide them with fuel, you cannot provide them with landing services, you cannot sell them tickets, or you will be knocked out of the dollar system,” Bessent said.Iranian news agency Tasnim said earlier, citing the Iranian Civil Aviation Organization, that flights from Tehran to Baghdad and Muscat had been cancelled from Wednesday.It said other international flights, including those to Istanbul, would continue to operate according to schedule.“Iranian travelers are not currently being admitted at the airport in Oman, and consultations regarding this matter are ongoing,” a spokesperson for Iran’s Civil Aviation Organization told Iran’s semi-official ISNA news agency.ISNA also reported that negotiations with Oman were ongoing and that other international flights, including those to Istanbul, would operate as scheduled.The latest disruptions follow Washington’s expanding sanctions campaign against Tehran.The United States has recently tightened restrictions targeting Iranian trade, energy and financial sectors, while also expanding secondary sanctions against foreign companies doing business with Iran.Tehran has nevertheless signalled that it remains open to talks mediated by Qatar aimed at finding a long-term resolution to the conflict, while maintaining a tough stance towards Washington.“It is in Washington’s interest to accept these conditions,” Iran’s security chief Mohsen Rezaei told Al Jazeera in an interview last week. “Trump’s threats will not achieve any results. We are prepared for a decisive war,” he added.The latest flight restrictions add to the growing pressure on Iran’s international air links as Washington seeks to isolate the country’s airlines through sanctions and restrictions on the services they rely on.