President Donald Trump said he hopes the grounding of Boeing Co.’s 737 Max family of passenger jets is only temporary but the U.S. had to take a “cautionary route” after the plane was involved in two fatal crashes.

“I hope it is going to be for a short period of time,” Trump told reporters gathered in the White House Thursday. “They have to find out what it is.”

The Federal Aviation Administration grounded Boeing’s 737 Max on Wednesday, reversing course after standing nearly alone by allowing the jets to remain in the air while aviation authorities and airlines across the globe halted flights in recent days.

FAA Acting Administrator Dan Elwell said the decision was based on new evidence that showed the 737 Max that crashed on Sunday in Ethiopia closely tracked another 737 Max crash five months ago in Indonesia, operated by Lion Air.

“We had to take a cautionary route,” Trump said. “The grounding of the planes yesterday was a big thing.”

He called Boeing “a great company,” adding “hopefully they’ll figure it out very quickly.”

Ethiopia has sent black boxes from the crashed Boeing jet to France for decoding after refusing to hand them to U.S. authorities that had kept the Max model flying after most other regulators grounded it.

Data from a new satellite network capable of tracking planes in high fidelity across the globe was critical in persuading the U.S. to join the rest of the world in grounding the jet, according to industry and regulatory officials.

“It became clear—to all parties, actually—that the track of the Ethiopian Airlines flight was very close and behaved very similarly to the Lion Air flight,” Elwell said.

FAA officials on Thursday morning privately briefed members of the House Transportation and Infrastructure Committee. Panel members including Democrat Steve Cohen of Tennessee and Republican Bruce Westerman of Arkansas said afterward they were given no indication of how long the grounding and investigation would last.