TEHRAN — Iranian airlines were forced to cancel some international flights on Wednesday after the US tightened sanctions on Iran’s aviation industry in a new effort to cripple its economy.

A travel agent in Tehran told AFP that flights to Baghdad, Muscat, Qatar, Georgia and Azerbaijan had all been suspended, but routes to multiple other destinations remained available, including China.

US Treasury Secretary Scott Bessent announced the new measures on Monday as part of an earlier threat to impose “economic D-Day” on Iran, an attempt to force it into submission following their nearly seven-month war.

But Iran’s aviation sector has already been a target of sanctions for years, and it remains unclear what the full impact will be and whether other countries will comply.

Even after the new sanctions took effect on Wednesday, a flight from Tehran operated by Mahan Air, one of Iran’s biggest carriers, landed in Guangzhou in China, according to tracking data from FlightRadar24.

China on Tuesday said it opposes the US sanctions and called them illegal. A flight to Shanghai was also due to depart on Wednesday, according to Tehran’s international airport.

Some flights to Istanbul were also scheduled, though others had been cancelled, the travel agent in Tehran told AFP.

“The situation is unstable and we are no longer selling tickets for the time being for fear of cancellations,” the  the agent said, requesting anonymity.

A Mahan flight from Kabul was also expected to arrive in Tehran around midday. According to the website for Tehran’s international airport, other connections to Turkey and Armenia also remained possible using smaller Iranian airlines, including Varesh.

Flights to Najaf in Iraq and Dubai in the United Arab Emirates were also scheduled.

Bessent on Monday vowed to “shut down” Iranian carriers and punish anyone doing business with them.