Airlines worldwide are diverting flights away from southern Iran, lengthening travel times, after the Federal Aviation Administration issued an edict barring American operators from the region amid escalating tensions with the Persian Gulf country.

Deutsche Lufthansa AG, Dutch carrier KLM and Qantas Airways Ltd of Australia are among carriers re-routing long-haul services to avoid the Strait of Hormuz, where the U.S. has blamed Iran for attacks on shipping and an American drone was shot down on Wednesday. United Airlines suspended flights between Newark, New Jersey, and Mumbai that regularly pass over the area.

“We closely follow all developments that may be related to the safety of airspace,” KLM, the Dutch arm of Air France-KLM, said. “The incident with the drone is reason not to fly over the Strait of Hormuz for the time being. This is a precautionary measure.”

A so-called notice to airmen from the FAA says airline flights above the Tehran flight-information region of the Persian Gulf and Gulf of Oman are prohibited until further notice “due to heightened military activities and increased political tensions.” Those circumstance present an inadvertent risk to planes in the form of “potential miscalculation or mis-identification.”

Chicago-based United said in an emailed statement that it had conducted “a thorough safety and security review” of its India service in light of recent events and decided to suspend the route.

Lufthansa has been avoiding the Strait of Hormuz and the Gulf of Oman since Thursday and has now expanded that zone in line with the FAA’s advice, which may result in “slightly longer flight times between Europe and India,” spokesman Thomas Jachnow said. Services to Tehran operated by the carrier and its Austrian Airlines unit aren’t affected.

British Airways, Singapore Airlines Ltd., Malaysia Airlines Bhd. and Qantas are also diverting inter-continental flights away from the area, according to reports, though not all global carriers are affected, with KLM’s sister company Air France saying relevant services are already routed further south.

In the region itself, Abu Dhabi-based Etihad Airways said it was evaluating the FAA directive and would consult with the United Arab Emirates civil aviation authority. Discount carrier FlyDubai said it would adjust some flight paths as a precautionary measure.

U.S. and Iranian officials have differing accounts of whether the high-altitude U.S. Navy drone was over international or Iranian waters when it was shot down. The downing comes after weeks of rising tensions, including attacks on cargo ships that the U.S. has also blamed on Iran.

Though an Iranian military officer was quoted by state-run media as saying the drone was shot down in order to send a “clear message,” President Donald Trump downplayed the incident, saying it “could have been somebody who was loose and stupid.”