Nearly 2,500 members of a union that represents three Boeing Co. defense locations in the St. Louis area voted to reject the company’s contract offer and plan to strike starting Aug. 1.

“We cannot accept a contract that is not fair and equitable, as this company continues to make billions of dollars each year off the backs of our hardworking members,” the International Association of Machinists and Aerospace Workers District 837 said in a statement on its website Sunday. The union said the company “previously took away a pension from our members” and isn’t compensating their 401(k) plans adequately.

The strike will affect workers in St. Louis and St. Charles in Missouri and Mascoutah, Illinois, who build military aircraft including the F-15, F-18, T-7A trainer and the MQ-25 unmanned refueler. The failed negotiations may portend an equally tough time for Boeing in the next round of contract talks for IAM’s much larger contingent at the company’s Seattle commercial-aircraft operations, which has about 30,000 Machinists members in a separate bargaining unit. 

“Boeing is disappointed with Sunday’s vote to reject a strong, highly competitive offer,” a company spokesman said via email. “We are activating our contingency plan to support continuity of operations in the event of a strike.”

In a statement on July 21, the union said Boeing offered “subpar” general wage increases, “no change in wage progression, and takeaways” in the 401(k).

Boeing said in May that it’s moving its headquarters from Chicago to Arlington, Virginia, to be nearer decision-makers at the Pentagon and elsewhere in the US government. Its shares have dropped 21% so far this year through Friday’s close. The company reported adjusted losses in 2020 and 2021.