The US Department of Justice (DOJ) says it is considering whether to prosecute Boeing over two deadly crashes involving its 737 Max aircraft.
The aviation giant breached the terms of an agreement made in 2021 that shielded the firm from criminal charges linked to the incidents, the DOJ said.
Boeing has denied that it violated the agreement.
The crashes - one in Indonesia in 2018, and another in Ethiopia in 2019 - killed a total of 346 people.
The plane maker failed to "design, implement, and enforce a compliance and ethics program to prevent and detect violations of the US fraud laws throughout its operations," the DOJ said.
Boeing said it was looking forward to the opportunity to respond to the Justice Department and "believes it honoured the terms of that agreement".
Under the deal, Boeing paid a $2.5bn (£1.98bn) settlement, while prosecutors agreed to ask the court to drop a criminal charge after a period of three years.
The DOJ said Boeing has until 13 June to respond to the allegations and that what it said would be taken into consideration as it decides what to do next.
Relatives of the victims have called for criminal action against the company.
“This is a positive first step, and for the families, a long time coming. But we need to see further action from DOJ to hold Boeing accountable", a lawyer for victims' families Paul G Cassell said in a statement.
Boeing has continued to face intense scrutiny over the safety of its aircraft after an unused door came off a new 737 Max shortly after take-off in January, leaving a gaping hole in the side of the plane.
BBC