U.S. aircraft manufacturer Boeing's efforts to defend the safety of its jets backfired Wednesday as the U.S. government bowed to international pressure to ground all Boeing 737 Max 8 and 9 aircraft.

The Federal Aviation Administration (FAA) initially refused to ground the 737 Max, cautioning against comparing the Ethiopian Airlines crash on Sunday with the October crash of the same model operated by Indonesia's Lion Air.

Pressure on the FAA mounted as a growing number of countries suspended flights by the plane or barred it from their airspace.

China was the first country in the world to suspend all Boeing 737 Max 8 airplanes and over 40 countries including Singapore, Australia, Canada and the European Union followed suit.

"Given that two accidents both involved the newly delivered Boeing 737-8 planes and happened during the take-off phase, they had some degree of similarity," China's Civil Aviation Administration said on its website, adding that the move was in line with the principle of zero tolerance for safety hazards.

"China has an excellent safety track record in civil aviation. In part, it comes from an absolute willingness to take decisions like these, even if it seems an overly cautious use of the powers," Gordon Orr, a senior adviser to McKinsey China, said on the social network LinkedIn.

The United States is the last major country in the world to act on Boeing with U.S. President Donald Trump telling a press event Wednesday that "all of those planes are grounded, effective immediately."

The FAA followed up on Trump's remarks with a statement, ordering the temporary grounding of Boeing 737 Max aircraft operated by U.S. airlines or in U.S. territory.

The move came hours after Canada announced it is pulling Boeing 737 Max aircraft from the sky.

"The grounding will remain in effect pending further investigation, including examination of information from the aircraft's data recorders and cockpit voice recorders," the FAA statement said.

The change of attitude, according to the FAA, was the "newly refined satellite data" and physical evidence on the crash site that linked the Ethiopian jet's movements to those of the Lion Air flight that plunged into the Java Sea off the coast of Indonesia shortly after departure, killing all 189 on board.

"That evidence aligns the Ethiopian flight closer to Lion Air, what we know happened to Lion Air," said Daniel Elwell, acting FAA administrator.

U.S. Democratic Senator Richard Blumenthal, who has called for the grounding of the aircraft since Monday, said the FAA took a right but "overdue" step.

"This step is right, but unacceptably overdue. Our nation should be leading, not lagging, in air safety. Strong, immediate scrutiny is necessary," Blumenthal tweeted, stressing that the U.S. public deserve to know "when this possible defect was 1st known, what will be done about it & who is responsible."

Boeing issued a statement saying it was supporting the temporary grounding "out of an abundance of caution."

Boeing said Monday it is planning to make a safety upgrade to software that is to be deployed across the 737 Max fleet in the coming weeks.

Despite Sunday's air crash in Ethiopia, Boeing said that the 737 Max is "a safe airplane that was designed, built and supported" by its skilled employees.

Ethiopia said it would send the black boxes recovered from the crash site to France for analysis, which could provide crucial information about what happened.

The 737 Max is Boeing's most important aircraft type, generating about one third of the company's operating profit.

According to the FAA, there are 387 Boeing 737 Max 8 jets in operation at 59 airlines worldwide, 74 of which are registered in the United States.

Since debuting in 2017, the Max jets, which is a key part of Boeing's effort to compete with rival Airbus, have plunged the company into its worst crisis in years.

Boeing shares decreased sharply on Wednesday shortly after Trump's decision to ground Boeing 737 Max 8 and 9 jets, but pared losses later in the day and closed up 0.46 percent. By far this week, the stock fell more than 10 percent.

A Boeing 737 Max 8 plane of Ethiopian Airlines crashed on Sunday morning, killing all 157 passengers and crew members on board. The plane crash was the second fatal incident involving the same model in five months.