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,

More than 3,200 union members who assemble Boeing's fighter jets in the St. Louis area and Illinois went on strike on Monday after rejecting a second contract offer the previous day. Boeing Defense said it was ready for the work stoppage and it will implement a contingency plan that uses non-labor workers.

Some 3,200 Boeing workers who build fighter jets in St. Louis and another Missouri site and one in Illinois are on strike, their union says.