By JON GAMBRELL Associated Press

DUBAI, United Arab Emirates (AP) — Airlines rerouted flights Friday to avoid airspace near the Strait of Hormuz after Iran shot down a U.S. military surveillance drone there and American aviation officials warned that commercial jetliners could be mistakenly attacked amid tensions between Tehran and Washington.

Local long-haul carriers Emirates and Etihad were among those that changed flight routes in an area that is home to major hubs of global air travel. That could further imperil the bottom lines of Gulf long-haul carriers, which already have faced challenges under the Trump administration.

"The threat of a civil aircraft shootdown in southern Iran is real," warned OPSGROUP, a company that advises airlines, citing as an example the downing of a Malaysia Airlines jetliner over eastern Ukraine in 2014, killing all 298 aboard.

The Federal Aviation Administration warned of a "potential for miscalculation or misidentification" in the region after an Iranian surface-to-air missile on Thursday brought down a U.S. Navy RQ-4A Global Hawk, an unmanned aircraft with a wingspan larger than a Boeing 737 jetliner and costing over $100 million. The U.S. said it made plans for limited strikes on Iran in response, but then called them off.

The FAA gave a similar warning in May to commercial airliners of the possibility of Iranian anti-aircraft gunners mistaking them for military aircraft, something dismissed by Tehran some 30 years after the U.S. Navy shot down an Iranian passenger jet, killing 290 people.

Iran had no immediate reaction to the U.S. announcement.

The FAA said its warning would affect the area of the Tehran Flight Information Region. An FAA map showed that area extending from Iran's southern border roughly a dozen miles out to sea along the Persian Gulf, the Gulf of Oman and the Strait of Hormuz, the narrow connection between the two bodies of water through which 20% of the world's crude oil passes.

"FAA remains concerned about the escalation of tension and military activity within close proximity to high volume civil air routes and the Iran's willingness to use long-range (surface-to-air missiles) in international airspace with little to no warning," the agency said. "As a result, there is concern about the potential for misidentification or miscalculation which could result in the inadvertent targeting of civil aviation."

The overall impact of the directive is rather minimal, said Ian Petchenik, a spokesman for the flight-tracking website Flightradar24, because avoiding that small portion of Iranian airspace is fairly simple from a technical perspective.

The few airlines affected would simply take northerly or southerly routes to avoid the area. He estimated that 100 flights might be affected in a 24-hour period.

"Long story short, if this is the new status quo, some flights are going to be marginally longer," Petchenik said.

But Henry Harteveldt, a travel analyst at Atmosphere Research Group in San Francisco, said longer routes put in place after the 2014 Malaysia Airlines disaster added about 90 minutes of flying time — and critically, fuel burn — in each direction for flights between Europe and parts of Asia.

"That can turn a flight from being a profitable one to a loss," he said. "This is a big deal."

Petchenik called the FAA statement "a cautious notice."

"This didn't come out of nowhere. The FAA had previously held that operators should be aware of tensions. They should acknowledge that there could be a risk to their aircraft. This is the logical step for them to take. It didn't come from nowhere. There should be no surprise on the air carriers' part," he added.

Qantas said it would reroute its London flights to avoid the Strait of Hormuz and Gulf of Oman. British Airways, KLM, Malaysia Airlines and Singapore Airlines said their flights would avoid the strait. Lufthansa said it would avoid both the Strait of Hormuz and the Gulf of Oman, as well as nearby land. However, it said it would continue its flights to Tehran.

The Persian Gulf 's long-haul carriers already have been battered by Trump's travel bans targeting predominantly Muslim countries, as well as an earlier ban on laptops in airplane cabins for Mideast carriers.

Emirates, the long-haul carrier in Dubai near the Strait of Hormuz, told AP it was "rerouting all flights away from areas of possible conflict." Its sister airline, the low-cost FlyDubai, said it "adjusted some of the existing flight paths in the region as a precautionary measure."

Etihad, based in Abu Dhabi, also said it would "change a number of the flight paths we operate."

Iran said the U.S. drone violated its airspace, while the U.S. called the missile fire "an unprovoked attack" in international airspace over the Strait of Hormuz. OPSGROUP said the Iranian weapons system that downed the drone was comparable to the Russian Buk system used against the Malaysia Airlines Boeing 777 in Ukraine.

"Any error in that system could cause it to find another target nearby — another reason not to be anywhere near this part of the Strait of Hormuz," OPSGROUP said.

A U.S. official said the military had prepared limited strikes on Iran in retaliation for downing the drone, but approval was abruptly withdrawn Thursday night before the attacks were launched. The official, who was not authorized to discuss the operation publicly and spoke on condition of anonymity, said the targets would have included radars and missile batteries.

President Donald Trump said the U.S. was "cocked & loaded" to attack three sites in Iran before he halted the assault over concerns about casualties.

The drone incident heightened the crisis gripping the wider region, which is rooted in Trump withdrawing the U.S. a year ago from the 2015 nuclear deal between Iran and world powers and imposing crippling new sanctions on Tehran. Recently, Iran quadrupled its production of low-enriched uranium to be on pace to break one of the deal's terms by next week while threatening to raise enrichment closer to weapons-grade levels on July 7 if Europe doesn't offer it a new deal.

Citing unspecified Iranian threats, the U.S. has sent an aircraft carrier to the region and deployed additional troops alongside the tens of thousands already there. All this has raised fears that a miscalculation or further rise in tensions could push the U.S. and Iran into an open conflict, 40 years after Tehran's Islamic Revolution.

"If we had done this, how would have America reacted?" asked Gen. Amir Ali Hajizadeh, the head of Guard's aerospace division, as he stood in Tehran near a display of debris that he said came from the U.S. drone. "If we had flown a drone near Washington, for example, would they allow us to get as close as 20 to 30 kilometers to their coasts? How would have they reacted?"

Associated Press writers Lolita C. Baldor and Deb Riechmann in Washington, David Rising in Berlin, Danica Kirka in London, David Koenig  in Dallas, Mike Corder in The Hague, Netherlands, and Mehdi Fattahi in Tehran, Iran, contributed.