New York. Boeing workers who build fighter jets went on strike Monday at midnight Central Daylight Time.

About 3,200 workers at Boeing facilities in St. Louis; St. Charles, Missouri; and Mascoutah, Illinois, voted to reject a modified four-year labor agreement with Boeing, the International Association of Machinists and Aerospace Workers union said 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.”

The vote followed members’ rejection last week of an earlier proposal from the troubled aerospace giant, which had included a 20 percent wage increase over four years.

“IAM District 837 members build the aircraft and defense systems that keep our country safe,” said Sam Cicinelli, Midwest territory general vice president for the union, in a statement. “They deserve nothing less than a contract that keeps their families secure and recognizes their unmatched expertise.”

At the time of the earlier vote, union leaders had recommended approving the offer, calling it a “landmark agreement” and saying it would improve medical, pension and overtime benefits.

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

“We’re disappointed our employees rejected an offer that featured 40 percent average wage growth and resolved their primary issue on alternative work schedules," said Dan Gillian, Boeing Air Dominance vice president and general manager, and senior St. Louis site executive.

"We are prepared for a strike and have fully implemented our contingency plan to ensure our non-striking workforce can continue supporting our customers.”

Boeing has been struggling after two of its Boeing 737 Max airplanes crashed, one in Indonesia in 2018 and the other in Ethiopia in 2019, killing 346 people. In June, one of Boeing's Dreamliner planes, operated by Air India, crashed, killing at least 260 people.

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.