Airlines across the Middle East and Europe have begun suspending or cancelling flights to Iran, including services to Tehran's Imam Khomeini International Airport, amid fears of a possible US attack on the country.
The wave of suspensions follows comments by US President Donald Trump threatening to take "strong action" against Iran if its crackdown on protesters continues.
The US embassy in Iran, which operates virtually, has also advised American nationals in the country to leave overland via neighbouring Turkey or Armenia.
Although no airspace closure or formal NOTAM has been issued over Iran, several carriers have taken precautionary steps by suspending, cancelling or rerouting flights.
Here is how major airlines have responded so far:
Emirates
Emirates cancelled all flights between Dubai and Tehran on Friday, with knock-on disruptions affecting scheduled services on Saturday. Some limited services have since resumed.
flydubai
flydubai, which operates flights from Dubai to several Iranian cities, cancelled services to Bandar Abbas, Bushehr, Isfahan, Tehran, Kerman, Lar, Mashhad and Shiraz on Friday. Flights on Saturday were also heavily disrupted, with only partial resumptions.
Qatar Airways
Qatar Airways cancelled all flights between Doha and Tehran on Friday and Saturday, as well as services to Mashhad and Shiraz. Flights to Tehran resumed on Sunday, though some routes remain subject to disruption.
Turkish Airlines
Turkish Airlines suspended all flights between Istanbul and several Iranian cities, including Tehran, Isfahan, Mashhad, Shiraz and Tabriz, from Friday through Sunday.
Pegasus Airlines
Turkey’s Pegasus Airlines cancelled most flights from Istanbul Sabiha Gökçen Airport to Iranian destinations, including Tehran, Isfahan, Mashhad, Shiraz and Tabriz, through the weekend.
Lufthansa
Germany's Lufthansa had already suspended flights to Tehran, citing security concerns and has postponed plans to resume services, extending the suspension further into January.
Austrian Airlines
Austrian Airlines extended the suspension of flights between Vienna and Tehran until at least 21 January, also citing security concerns.
British Airways
British Airways, which does not operate flights to Iran, has also paused flights to Bahrain, widening the impact of regional tensions beyond Iran.
The British flag carrier halted operations to the Gulf kingdom, home to the US Navy's Fifth Fleet, from 16 January to 20 January, according to its website.
A spokesperson said the suspension was a precautionary measure and that the airline would continue to monitor developments in the region.
Editor's note: This article was updated on 16 January at 17:15 GMT to include British Airways' suspension of flights to Bahrain amid rising regional tensions.