The strike adds pressure to Boeing's turnaround efforts, as its defense and space division contributes roughly a third of the company's revenue. The affected workers produce fighter jets such as the F-15 and the T-7 training jet, as well as missiles and munitions. They also manufacture components for Boeing's 777X commercial jets. In March, Boeing secured a contract to design and build the US's next-generation stealth fighter, the F-47, beating Lockheed Martin Corp. (NYSE: LMT) for the multibillion-dollar program.