More than three thousand Boeing defence workers went on strike on Monday, in a fresh blow to the embattled aviation giant.

It comes after union members at operations in Missouri and Illinois, who build F-15 fighter jets and other military aircraft, voted against the firm’s latest offer over pay, work schedules and pensions.

“We’re disappointed our employees rejected an offer that featured 40% average wage growth”, Dan Gillian, who is the vice president of Boeing’s Air Dominance unit, said in a statement.

Boeing is struggling to turn itself around after a series of problems, including safety issues and a damaging almost eight-week walkout by passenger plane workers last year.

The walkout is being led by a local branch of the International Association of Machinists and Aerospace Workers (IAM) based in St Louis, where Boeing’s defence manufacturing hub is located.

“3,200 highly-skilled IAM Union members at Boeing went on strike at midnight because enough is enough. This is about respect and dignity, not empty promises,” the union posted on X.

IAM is one of America’s largest unions, representing roughly 600,000 members in the aerospace, defence, shipbuilding and manufacturing industries.

It is the first walkout at Boeing’s defence business since 1996, when work stopped for more than three months.

But last week Boeing’s chief executive Kelly Ortberg downplayed the potential impact of the walkout.

He highlighted that it would be a lot smaller than a strike last year involving around 30,000 passenger jet workers that cost the firm billions of dollars.

“I wouldn’t worry too much about the implications of the strike. We’ll manage our way through that,” said Mr Ortberg.

Boeing has been hit by a series of crises in recent years, including two fatal crashes and a dramatic mid-air blowout of a piece of one of its planes.

In 2018, a Boeing 737 crashed after taking off from Jakarta, Indonesia, killing all 189 people on board. A few months later, another 157 people died when a Boeing plane crashed shortly after take-off in Ethiopia.

Separately in 2024, a panel fitted over an unused emergency exit of a Boeing 737 Max came off mid-flight.

The company delivered just 348 aircraft to its customers last year, its lowest output since the pandemic.