Boeing’s new chief executive on Friday announced plans to reduce its work force by 10 percent, or about 17,000 jobs, as he seeks to restructure the company in an effort to slash costs and improve production of planes, which has been plagued by numerous delays.

Kelly Ortberg, who became chief executive in August, told employees in a memo that Boeing, which last reported an annual profit in 2018, faced big problems and needed to change how it did business in ways that play to its strengths.

The announcement on Friday comes as the company deals with a costly and disruptive strike that began nearly a month ago, when members of its largest union rejected a contract offer and walked off the job. The union, the International Association of Machinists and Aerospace Workers, represents more than 33,000 Boeing employees.

Boeing on Friday also reported $5 billion in new costs associated with several commercial and defense programs.

“Our business is in a difficult position, and it is hard to overstate the challenges we face together,” Mr. Ortberg said. “Beyond navigating our current environment, restoring our company requires tough decisions and we will have to make structural changes to ensure we can stay competitive and deliver for our customers over the long term.”

The cuts, which will include layoffs and not filling positions as employees leave, amount to a 10 percent reduction of Boeing’s 170,000 employees. Mr. Ortberg said that the cuts will take place across the company, affecting executives, managers and production workers.