Several international airlines said Wednesday they would avoid Iranian and Iraqi airspace after Tehran fired ballistic missiles at bases housing U.S. troops in Iraq.

Lufthansa and its Austrian Airlines unit nonetheless decided to maintain flights to Tehran this week, a statement said.

Iran launched more than 20 missiles at bases housing U.S. troops in the early hours, officials in Washington and Tehran said.

Iran’s supreme leader called the attacks a “slap in the face” for the United States after a U.S. drone strike killed Iranian military commander Qassem Soleimani near Baghdad International Airport last week.

Japanese airlines All Nippon Airways and Japan Airlines Co., and Hong Kong-based Cathay Pacific said their planes do not fly through the airspace affected by the latest escalation.

In Germany, Lufthansa said it had halted overflights of Iran and Iraq until further notice. But it added that Tehran Airport was open and that there were no security restrictions for the approach route or the area around the airport. Lufthansa also plans to resume the route Thursday, the airline said.

Lufthansa said it had canceled a flight scheduled Saturday to the northern Iraqi city of Irbil.

Meanwhile, the U.S. Federal Aviation Administration banned U.S.-registered carriers from flying over Iraq, Iran and the Gulf, citing the potential for “misidentification” of aircraft.

Its Russian counterpart, the Federal Air Transport Agency, said it was recommending that airlines avoid the air space over Iran, Iraq and the Persian and Oman gulfs “due to information about current risks for safety of international passenger flights.

The move came on the same day that a Ukrainian airliner crashed near Tehran killing all 176 on board.The region is a central corridor for flights between Europe and Asia, but aircraft can be rerouted fairly easily.

An Air France spokesman said: “Air France has decided to suspend until further notice all flights through Iranian and Iraqi airspace.”

Partner airline KLM was doing likewise, a spokesman said.

Carriers that took similar decisions included Air Canada, Air India, Malaysia Airlines, Polish LOT, Singapore Airlines, Swiss and Quantas.

Vietnam Airlines said it would make “appropriate adjustments” to routes to avoid areas of potential instability, although its regular flight paths to Europe do not pass over Iran or Iraq.

UAE carriers Emirates Airline and low-cost Flydubai scrubbed flights to Baghdad for “operational reasons.”

Bahrein Airways and Kuwait Airways had already suspended flights to Iraq shortly after Soleimani’s assassination, and on Tuesday, EgyptAir said it would as well for three days.