Boeing Co. expects more than 3,200 union workers at three St. Louis-area plants that produce U.S. fighter jets to strike after they rejected a proposed contract Sunday that included a 20% wage increase over four years.

Union members who assemble Boeing's fighter jets in the St. Louis area have "overwhelmingly voted" to reject the company's contract offer on Sunday.

Boeing (NYSE:BA) is at risk of a work stoppage at its St. Louis-area defense facilities after union members overwhelmingly rejected a proposed labor contract that included a 20% wage increase over four years.