United Airlines has temporarily stopped flying between the New York area and Mumbai because of security concerns about Iranian airspace, the carrier said Thursday night.

United said it had “conducted a thorough safety and security review” before deciding to indefinitely scrap the flight. United canceled its late-night Thursday departure from Mumbai to Newark, as well as its evening flight from Newark to Mumbai “because of an air space restriction over Western Asia,” according to a message on United.com.

The decision came after the United States accused Iran of shooting down one of its military drones. Iran admitted to the incident, but there’s some question about whether it happened over international airspace or over Iran’s airspace. The U.S. government, which has said the drone was over international waters, has been weighing how to respond.

Other airlines continued to fly over Iran on Thursday, including Lufthansa, which operates codeshare service with United. But United, only one of three global U.S. carriers now flying to India, apparently decided it was not worth the risk.

In recent days United’s flight to Mumbai typically has crossed over Northern Europe and then proceeded southeast, over the Caspian Sea and through Eastern Iran, according to Flight Radar 24. Sometimes airlines can keep flying a route by adding flight time to avoid hotspots, but that would be challenging here.

In a statement United said it will rebook customers who planned to fly to Mumbai.

“We are contacting our customers to provide this update and assist those who may need rebooking options,” it said. “We continue to explore all our options and remain in close contact with relevant government authorities in order to provide our customers with the most efficient travel experience under these circumstances.”

New Development

After United halted its flights, the U.S. government issued a notice to airmen telling pilots they could not fly over Iran due to “heightened military activities and increased political tensions in the region.”

The notice is only binding for U.S.-flagged airliners. The Federal Aviation Administration said there was a potential for “miscalculation” or “misidentification” of civilian airliners.

“The risk to U.S. civil aviation is demonstrated by the Iranian surface-to-air missile shoot down of a U.S. unmanned aircraft system on 19 June 2019 while it was operating in the vicinity of civil air routes above the Gulf of Oman,” the government said.

Delhi Also Suspended

United usually has two India routes, but the second one, from Newark to Delhi, has been suspended because of a different geopolitical problem. Pakistan has closed some of its airspace because of a feud with India, making it difficult for U.S. airlines to fly to Delhi using a reasonable route.

For awhile United had been making a fuel and crew stop in Germany so it could keep flying to Delhi by flying a circuitous route. But ultimately that stop proved too costly.

United told employees earlier this month that flying the route nonstop from Newark was impossible because avoiding Pakistan took too much time.

“We have also received questions from employees asking why our Star Alliance Partner Air India continues to operate this route while our service remains suspended,” United said in a message to employees. “FAA crew duty time limitations – which apply only to U.S. carriers like United – do not permit us to extend the flight time adequately to avoid Pakistan’s airspace.”

United is supposed to start a third India flight, from San Francisco to Delhi, in December.

This story was updated with information about the notice to airmen for U.S. pilots and airlines. 

Photo Credit: A United Airlines Boeing 777-300ER. The airline has been using the aircraft for Mumbai flights. United Airlines