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.

Axar.az informs, citing Reuters, Boeing Defense said it was ready for the work stoppage and it will implement a contingency plan that uses non-labor workers.

According to the company, the rejected four-year contract would have raised the average wage by roughly 40 percent and included a 20 percent general wage increase and a $5,000 ratification bonus. It also included increasing periodic raises, more vacation time and sick leave.

“We’re disappointed our employees in St. Louis rejected an offer that featured 40 percent average wage growth,” Dan Gillian, Boeing vice president and general manager of the St. Louis facilities, said in a statement.

Members of the International Association of Machinists and Aerospace Workers’ District 837 “deserve a contract that reflects their skill, dedication, and the critical role they play in our nation’s defense,” District 837 head Tom Boelling said in a statement.