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,

The strike involves roughly 3,200 workers at three Boeing sites, including its St. Louis hub, which is expected to be central to the F-47 program.

About 3,200 union members at Boeing facilities in Michigan and Illinois went on strike at midnight on Monday after rejecting an offer from the company, the union said.