Workers at three Boeing defense manufacturing plants will vote Wednesday on a modified labor contract proposal, temporarily avoiding a strike that was slated to start as soon as Monday.

The International Association of Machinists and Aerospace Workers said that the aerospace company made a new contract offer after an overnight bargaining session between the two sides. About 2,500 members of the union’s District 837 work at three St. Louis-area Boeing plants that make weapons and military aircraft including the F-15 combat jet, the T-7A trainer and the MQ-25 refueling drone.