Scott Bessent says airports and companies servicing Iranian carriers risk being cut off from the US dollar system.

United States Treasury Secretary Scott Bessent says Iranian airlines could effectively be shut out of international travel from Wednesday, as Washington threatens foreign companies with secondary sanctions if they continue servicing the country’s carriers.

“On September 23, all the Iranian airlines will be shut down around the world,” Bessent told CNBC on Monday.

The warning is aimed not just at the airlines themselves, but at the airports, fuel suppliers, ticketing companies and other businesses they rely on to operate abroad.

“If they land, 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.

The threat marks the latest step in US President Donald Trump administration’s escalating economic campaign against Tehran, which has continued alongside the war between the US and Iran.

Earlier this month, the US Treasury imposed sanctions on all remaining Iranian airlines that had not already been targeted, as well as companies outside Iran accused of supporting the country’s aviation sector.

Iran’s aviation industry was already heavily constrained by years of US sanctions, which have made it difficult for carriers to buy new aircraft and obtain spare parts and maintenance services.

The measures are part of a much broader sanctions regime aimed at isolating Iran from the international financial system. US secondary sanctions threaten foreign companies that do business with Iran across sectors including energy, shipping, technology, gold and digital assets with penalties of their own.

China ‘very engaged’ on Iran sanctions

Bessent’s comments came a day after talks with Chinese Vice Premier He Lifeng, ahead of Trump’s meeting with Chinese President Xi Jinping on Thursday.

China is one of Iran’s most important economic partners and diplomatic backers, making Beijing’s cooperation potentially significant to Washington’s efforts to financially isolate Tehran.

Bessent said Chinese officials had been “very engaged” in the US pressure campaign. Washington was holding what he described as positive talks with Chinese financial authorities, including People’s Bank of China Governor Pan Gongsheng, about compliance with US sanctions on Iran.