The strike started at three Midwest manufacturing plants after about 3,200 local members of the International Association of Machinists and Aerospace Workers voted Sunday to reject a modified four-year labor agreement,

Employees at Boeing’s St. Louis defense factories rejected a contract offered by the aerospace giant Sunday afternoon and around 3,200 workers began striking starting at midnight—the first walk out the company has faced at its St. Louis defense hub since 1996.

About 3,200 workers who build F-15 fighter jets and other military aircraft voted to reject the firm's latest contract deal.