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(AP) — Airlines are coming under increasing scrutiny for continuing to fly in Iran after a missile barrage and warnings by U.S. safety regulators about the dangerous conditions.

American, British and Canadian officials said Thursday it is “highly likely” that Iran shot down a Ukrainian airliner near Tehran this week, possibly by accident during a time of high political tension in the region.

About two and one-half hours before the Ukraine International Airlines jet with 176 people on board took off, the Federal Aviation Administration issued emergency orders that prohibited American pilots and airlines from flying over Iran, the Persian Gulf or the Gulf of Oman.

The notices warned that heightened military activity and political tension in the Middle East raised “an inadvertent risk” to U.S. aircraft “due to the potential for miscalculation or mis-identification.”

Foreign airlines aren’t bound by FAA directives, but they often follow them. In this case, however, several large international carriers including Lufthansa, Turkish Airlines, Qatar Airways and Aeroflot continued to fly in and out of Tehran after the missiles were launched, after the FAA warning, and after the Ukrainian jetliner crashed, according to data from Flightradar24, which tracks flights around the world.

“It was awfully peculiar and awfully risky,” said Peter Goelz, a former managing director of the U.S. National Transportation Safety Board. “That’s a theater of war and these guys were acting like there was nothing going on.”

Goelz said airlines should have canceled all flights when Iran fired a barrage of missiles at military bases inside Iraq that house U.S. troops. Those attacks occurred the night before the Ukrainian plane was scheduled to leave Tehran.

Despite the FAA warnings, planes kept flying at Tehran’s Imam Khomeini International Airport. After the FAA notices, 12 airliners took off or landed without incident early Wednesday, according to data from Flightradar24. Ukraine International Airlines flight 752 was No. 13.

By late Thursday, some major airlines had changed their thinking. A Lufthansa flight from Frankfurt to Tehran turned back over Romania and headed back toward Germany. Austrian Airlines said on Twitter that “due to the latest reports and the changed assessment of the security situation for the airspace around Tehran airport,” it canceled a flight Thursday and another Friday. Turkish Airlines temporarily halted flights to Iran and Iraq.