The United States has finally joined the rest of the world in grounding Boeing aircraft models involved in a series of tragic accidents.

President Donald Trump announced on Wednesday an emergency order grounding all Boeing’s 737 Max 8 and 9 jets amid resistance on the part of the Federal Aviation Administration (FAA).

Airlines across the world grounded Boeing Max airliners after the crash of an Ethiopian Airlines aircraft on Sunday. The accident followed a similar incident less than six months ago, when another Max crashed.

Trump told reporters that any of the planes “will be grounded upon landing at the destination.…  Pilots have been notified. Airlines have been all notified.”

Despite accusations that Boeing malpractice contributed to the crashes, Trump praised the firm in his comments.

“Boeing is an incredible company,” he said. “They are working very, very hard right now, and hopefully they’ll very quickly come up with the answer, but until they do, the planes are grounded.”

The US delayed the decision, even while preliminary evidence pointed to unresolved safety issues with the Max jets, prompting criticism of US regulators.

The two recent incidents have led to allegations of negligence on the part of Boeing, with some experts arguing that the company failed to properly train pilots in advance of technology upgrades.

The hesitation to ground the aircraft also raised questions about the role of aviation-industry lobbyists in the FAA, including the acting head of the agency, Daniel Elwell. Elwell was formerly a senior official at the largest trade group representing US airlines.

Others have voiced concerns about the close relationship between the Trump administration and Boeing. The administration’s acting defense secretary, Patrick Shanahan, worked at Boeing for three decades before being tapped to fill his current role after General James Mattis’ abrupt resignation earlier this year. A watchdog group on Wednesday filed a complaint accusing Shanahan of promoting Boeing’s interests while serving as defense chief.

But concerns regarding the US aviation safety regulators are not new. Lawmakers have been pushing for greater oversight for years, including after a report last year exposed lax FAA oversight.

Several US lawmakers said they would issue subpoenas to regulators, including the FAA’s Elwell, as well as Boeing executives, to testify before Congress.