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.

Machinists at Boeing's combat aircraft facilities have voted to strike from 4 August, rejecting the company's revised contract offer despite improved pension terms.