Boeing has grounded its entire global fleet of 737 Max aircraft after investigators uncovered new evidence at the scene of the fatal Ethiopian Airlines crash.
The US plane-maker said it would suspend all 371 of the aircraft.
The Federal Aviation Administration said fresh evidence as well as newly refined satellite data prompted the decision to temporarily ban the jets.
The FAA had previously held out while many countries banned the aircraft.
The crash on Sunday in Addis Ababa killed 157 people.
It was the second fatal Max 8 disaster in five months after one crashed over Indonesia in October, claiming 189 lives.
Boeing said it “continues to have full confidence in the safety of the 737 Max”.
However, it said that after consultation with the FAA and the National Transportation Safety Board – which is conducting an investigation into the Ethiopian Airlines crash – it had decided to ground the flights “out of an abundance of caution and in order to reassure the flying public of the aircraft’s safety”.
The FAA said: “The grounding will remain in effect pending further investigation, including examination of information from the aircraft’s flight data recorders and cockpit voice recorders.”
American Airlines said 24 of its aircraft would be affected by the suspension, adding: “Our teams will be working to rebook customers as quickly as possible, and we apologise for any inconvenience.”
United Airlines said that its Max aircraft account for roughly 40 flights a day.
It said: “Through a combination of spare aircraft and rebooking customers, we do not anticipate a significant operational impact as a result of this order.”
Earlier on Wednesday, Canada grounded the planes after its transport minister Marc Garneau said he had received new evidence about the crash.
He said that satellite data showed possible similarities between flight patterns of Boeing 737 Max planes operating in Canada and the Ethiopian Airlines plane that crashed.
He said: “As a result of new data that we received this morning, and had the chance to analyze, and on the advice of my experts and as a precautionary measure, I issued a safety notice.”
Dennis Muilenburg, president, chief executive and chairman of Boeing, said: “We are doing everything we can to understand the cause of the accidents in partnership with the investigators, deploy safety enhancements and help ensure this does not happen again.”