NEW YORK (AP) — Boeing workers who build fighter jets went on strike Monday at midnight Central Daylight Time.

Approximately 3,200 employees working at Boeing locations in St. Louis; St. Charles, Missouri; and Mascoutah, Illinois, decided to turn down a revised four-year labor contract with Boeing, as announced by the International Association of Machinists and Aerospace Workers union on Sunday.

In a post on X, the union said: “3,200 highly-skilled IAM Union members at Boeing went on strike at midnight because enough is enough.”

This decision came after members had already rejected a prior proposal from the embattled aerospace company, which had promised a 20% wage increase spread over four years.

Sam Cicinelli, the Midwest territory general vice president for the union, commented, “IAM District 837 members are responsible for constructing the aircraft and defense systems that protect our nation. They deserve a contract that not only secures their families but also acknowledges their unparalleled expertise.”

During the previous vote, union leaders had advised members to accept the proposal, labeling it a “landmark agreement,” and highlighting potential enhancements in medical, pension, and overtime benefits.

The union members rejected the latest proposal after a weeklong cooling-off period.

Boeing Air Dominance vice president and general manager, as well as senior St. Louis site executive, Dan Gillian expressed disappointment, stating, “We’re disheartened our employees turned down an offer that included an average 40% wage growth and addressed their main concern regarding alternative work schedules. We are ready for a strike and have our contingency strategies in place to ensure our remaining workforce continues to support our clients.”

Boeing has been encountering difficulties following tragic incidents involving two Boeing 737 Max airplanes, crashing in Indonesia in 2018 and Ethiopia in 2019, resulting in 346 fatalities. In June, a Boeing Dreamliner jet, operated by Air India, crashed, leading to at least 260 fatalities.

Last week, Boeing reported that its second-quarter revenue had improved and losses had narrowed. The company lost $611 million in the second quarter, compared to a loss of $1.44 billion during the same period last year.