Boeing Co. is bracing for the first strike in nearly three decades at its St. Louis-area defense factories after union members rejected the company’s modified contract offer.

(Reuters) -Unionized workers who assemble Boeing's fighter jets in the St. Louis area rejected Boeing's latest contract offer on Sunday and will strike at midnight on Monday, the International Association of Machinists and Aerospace Workers union said.

Employees at Boeing’s St. Louis defense factories rejected a contract offered by the aerospace giant Sunday afternoon, setting the stage for about 3,200 workers to walk off the job starting at midnight—the first strike the company has faced at its St. Louis defense hub since 1996.