Boeing Co. is facing the prospect of a work stoppage at its St. Louis–area defense operations after about 3,200 members of the International Association of Machinists and Aerospace Workers District 837 voted on 27 July to reject a new four-year labor agreement. The proposal would have raised wages by roughly 20% over the contract term, but the union said the offer failed to address key concerns over benefits and working conditions. Under U.S. labor rules, the rejection triggers a seven-day cooling-off period; absent a new agreement, a strike could begin as soon as early August. Boeing said it was “disappointed” by the vote, called the package its most generous ever for the unit, and confirmed it has activated contingency plans. No further bargaining sessions have been scheduled. A walkout would halt assembly of the F-15 and F/A-18 fighter jets and other military programs housed at the company’s facilities in St. Louis, St. Charles, and Mascoutah, potentially straining Boeing’s defense division at a time of heightened demand for combat aircraft. The labor setback follows weeks of negotiations that union officials earlier described as producing a tentative “landmark” accord, underscoring persistent tensions over pay and benefits in the U.S. aerospace sector.